Copyright © 2021 W3C ® ( MIT , ERCIM , Keio , Beihang ). W3C liability , trademark and permissive document license rules apply.
Privacy is an essential part of the Web [ ETHICAL-WEB ]. This document provides definitions for privacy and related concepts that are applicable worldwide. It also provides a set of privacy principles that should guide the development of the Web as a trustworthy platform. Users of the Web would benefit from a stronger relationship between technology and policy, and this document is written to work with both.
This document was published as a Draft Finding by the Web Privacy Principles Task Force , which was convened by the Technical Architecture Group (TAG) and the Privacy Interest Group (PING) . Publication as a Draft Finding does not imply endorsement by the TAG or by the W3C Membership. This draft does not yet reflect the consensus of the task force and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to cite this document as anything other than a work in progress.
It does not contain any normative content.
This document will continue to evolve and the task force will issue updates as often as needed. At the conclusion of the task force, it is intended to be adopted by the TAG as a Finding.
Privacy is essential to trust, and trust is a cornerstone value of the Web [ RFC8890 ]. In much of everyday life, people have little difficulty assessing whether a given flow of information constitutes a violation of privacy or not [ NYT-PRIVACY ]. However, in the digital space, users struggle to understand how their data may flow between contexts and how such flows may affect them, not just immediately but at a much later time and in completely different situations. Some actors then seize upon this confusion in order to extract and exploit personal data at unprecedented scale.
The goal of this document is to define all the terms that may prove useful in developing technology and policy that relate to privacy and personal data . It additionally provides a toolbox to support the common need that is privacy threat modelling, the frequent debate over consent, and the under-developed set of issues in privacy that are of a collective, relational nature.
Personal data is a regulated object, and this document naturally recognises the jurisdictional primacy of existing data protection regimes. However, the global nature of the Web means that, as we develop technology, we benefit from shared concepts that guide the evolution of the Web as a system built for its users [ RFC8890 ]. A clear and well-defined view of privacy on the Web, grounded in an up-to-date understanding of the state of the art, can hopefully help the Web's constituencies thrive across jurisdictional disparity, with the shared understanding that the law is a floor, not a ceiling.
This
section
provides
a
number
of
elementary
building
blocks
from
which
to
establish
a
shared
understanding
of
privacy.
Some
of
the
definitions
below
build
atop
the
work
in
Tracking
Preference
Expression
(DNT)
[
tracking-dnt
].
A
user
(also
person
or
data
subject
)
is
any
natural
person.
We
define
personal
data
as
any
information
relating
to
a
person
such
that:
Data
is
permanently
de-identified
when
there
exists
a
high
level
of
confidence
that
no
human
subject
of
the
data
can
be
identified,
directly
or
indirectly
(e.g.,
via
association
with
an
identifier,
user
agent,
or
device),
by
that
data
alone
or
in
combination
with
other
retained
or
available
information,
including
as
being
part
of
a
group.
Note
that
further
considerations
relating
to
groups
are
covered
in
the
Collective
Issues
in
Privacy
section.
Data
is
pseudonymous
when:
the
identifiers
used
in
the
data
are
under
the
direct
and
exclusive
control
of
the
first
party
;
and
when
these
identifiers
are
shared
with
a
third
party
,
they
are
made
unique
to
that
third
party
such
that
if
they
are
shared
with
more
than
one
third
party
these
cannot
then
match
them
up
with
one
another;
and
there
is
a
strong
level
of
confidence
that
no
third
party
can
match
them
to
any
data
other
than
that
obtained
through
interactions
with
the
first
party
;
and
any
third
party
receiving
such
identifiers
is
barred
(eg.
based
on
legal
terms)
from
sharing
them
or
the
related
data
further;
and
technical
measures
exist
to
prevent
re-identification
or
the
joining
of
different
data
sets
involving
these
identifiers,
notably
against
timing
or
k-anonymity
attacks;
and
there
exist
contractual
terms
between
the
first
party
and
third
party
describing
the
limited
purpose
for
which
the
data
is
being
shared.
This
can
ensure
that
pseudonymous
data
is
used
in
a
manner
that
provides
a
minimum
degree
of
governance
such
that
technical
and
procedural
means
to
guarantee
the
maintenance
of
pseudonymity
are
preserved.
Note
that
pseudonymity
,
on
its
own,
is
not
sufficient
to
render
data
processing
appropriate
.
A
vulnerable
person
is
a
person
who,
at
least
in
the
context
of
the
processing
being
discussed,
are
unable
to
exercise
sufficient
self-determination
for
any
consent
they
may
provide
to
be
receivable.
This
includes
for
example
children,
employees
with
respect
to
their
employers,
people
in
some
situations
of
intellectual
or
psychological
impairment,
or
refugees.
A
party
is
an
entity
that
a
person
The
first
party
is
a
party
with
which
the
user
intends
to
interact.
Merely
hovering
over,
muting,
pausing,
or
closing
a
given
piece
of
content
does
not
constitute
a
user
's
intent
to
interact
with
another
party,
nor
does
the
simple
fact
of
loading
a
party
embedded
in
the
one
with
which
the
user
intends
to
interact.
In
cases
of
clear
and
conspicuous
joint
branding,
there
can
be
multiple
first
parties
.
The
first
party
is
necessarily
a
data
controller
of
the
data
processing
that
takes
places
as
a
consequence
of
a
user
interacting
with
it.
A
third
party
is
any
party
other
than
the
user
,
the
first
party
,
or
a
service
provider
acting
on
behalf
of
either
the
user
or
the
first
party
.
A
service
provider
or
data
processor
is
considered
to
be
the
same
party
as
the
entity
contracting
it
to
perform
the
relevant
processing
if
it:
A
data
controller
is
a
party
that
determines
the
means
and
purposes
of
data
processing.
Any
party
that
is
not
a
service
provider
is
a
data
controller
.
The
Vegas
Rule
is
a
simple
implementation
of
privacy
in
which
"
what
happens
with
the
first
party
stays
with
the
first
party
."
Put
differently,
it
describes
a
situation
in
which
the
first
party
is
the
only
data
controller
.
Note
that,
while
enforcing
the
Vegas
Rule
provides
a
rule
of
thumb
describing
a
necessary
baseline
for
appropriate
data
processing
,
it
is
not
always
sufficient
to
guarantee
appropriate
processing
since
the
first
party
can
process
data
inappropriately
.
A
party
processes
data
if
it
carries
out
operations
on
personal
data
,
whether
or
not
by
automated
means,
such
as
collection,
recording,
organisation,
structuring,
storage,
adaptation
or
alteration,
retrieval,
consultation,
use,
disclosure
by
transmission,
sharing
,
dissemination
or
otherwise
making
available,
selling
,
alignment
or
combination,
restriction,
erasure
or
destruction.
A
party
shares
data
if
it
provides
it
to
any
other
party
.
Note
that,
under
this
definition,
a
party
that
provides
data
to
its
own
service
providers
is
not
sharing
it.
A
party
sells
data
when
it
shares
it
in
exchange
for
consideration,
monetary
or
otherwise.
The
purpose
of
a
given
processing
of
data
is
an
anticipated,
intended,
or
planned
outcome
of
this
processing
which
is
achieved
or
aimed
for
within
a
given
context
.
A
purpose
,
when
described,
should
be
specific
enough
to
be
actionable
by
someone
familiar
with
the
relevant
context
(ie.
they
could
independently
determine
means
that
reasonably
correspond
to
an
implementation
of
the
purpose
).
The
means
are
the
general
method
of
data
processing
through
which
a
given
purpose
is
implemented,
in
a
given
context
,
considered
at
a
relatively
abstract
level
and
not
necessarily
all
the
way
down
to
implementation
details.
Example:
the
user
will
have
their
preferences
restored
(purpose)
by
looking
up
their
identifier
in
a
preferences
store
(means)
.
A
context
is
a
physical
or
digital
environment
that
a
person
interacts
with
for
a
purpose
of
their
own
(that
they
typically
share
with
other
person
who
interact
with
the
same
environment).
A
context
can
be
further
described
through:
A
context
carries
context-relative
informational
norms
that
determine
whether
a
given
data
processing
is
appropriate
(if
the
norms
are
adhered
to)
or
inappropriate
(when
the
norms
are
violated).
A
norm
violation
can
be
for
instance
the
exfiltration
of
personal
data
from
a
context
or
the
lack
of
respect
for
transmission
principles
.
When
norms
are
respected
in
a
given
context
,
we
can
say
that
contextual
integrity
is
maintained;
otherwise
that
it
is
violated
([
PRIVACY-IN-CONTEXT
],
[
PRIVACY-AS-CI
]).
We
define
privacy
as
a
right
to
appropriate
data
processing
.
A
privacy
violation
is,
correspondingly,
inappropriate
data
processing
[
PRIVACY-IN-CONTEXT
].
Note
that
a
first
party
can
be
comprised
of
multiple
contexts
if
it
is
large
enough
that
people
would
interact
with
it
for
more
than
one
purpose
.
Sharing
personal
data
across
contexts
is,
in
the
overwhelming
majority
of
cases,
inappropriate
.
Your
cute
little
pup
uses
Poodle
Naps
to
find
comfortable
places
to
snooze,
and
Poodle
Fetch
to
locate
the
best
sticks.
Napping
and
fetching
are
different
contexts
with
different
norms,
and
sharing
data
between
these
contexts
is
a
privacy
violation
despite
the
shared
ownership
of
Naps
and
Fetch
by
the
Poodle
conglomerate.
Colloquially,
tracking
is
understood
to
be
any
kind
of
inappropriate
data
collection.
Additionally,
privacy
labour
is
the
practice
of
having
a
person
carry
out
the
work
of
ensuring
data
processing
of
which
they
are
the
subject
is
appropriate
,
instead
of
having
the
parties
be
responsible
for
that
work
as
is
more
respectable.
The
user
agent
acts
as
an
intermediary
between
a
user
and
the
web.
The
user
agent
is
not
a
context
in
that
it
is
expected
to
coincide
with
the
subject
and
operate
exclusively
in
the
subject
's
interest.
It
is
not
the
first
party
.
The
user
agent
serves
the
user
in
a
relationship
of
fiduciary
agency
:
it
always
puts
the
user
's
interest
first,
up
to
and
including,
on
occasion,
protecting
the
user
from
themselves
by
preventing
them
from
carrying
out
a
harmful
decision,
or
at
the
very
least
by
speed-bumping
it
[
FIDUCIARY-UA
].
For
example,
the
user
agent
will
make
it
difficult
for
the
user
to
connect
to
a
site
the
authenticity
of
which
is
hard
to
ascertain,
will
double-check
that
the
user
really
intends
to
expose
a
sensitive
device
capability,
or
will
prevent
the
user
from
consenting
to
permanent
monitoring
of
their
behaviour.
Its
fiduciary
duties
include
[
TAKING-TRUST-SERIOUSLY
]:
These
duties
ensure
the
user
agent
will
care
for
the
user.
It
is
important
to
note
that
there
is
a
subtle
difference
between
care
and
data
paternalism
which
is
that
the
latter
purports
to
help
in
part
by
removing
agency
("
don't
worry
about
it,
so
long
as
your
data
is
with
us
it's
safe,
you
don't
need
to
know
what
we
do
with
it,
it's
all
good
because
we're
good
people
")
whereas
care
aims
to
support
people
by
enhancing
their
agency
and
sovereignty.
A
person
's
identity
is
the
set
of
characteristics
that
define
them.
Their
identity
in
a
context
is
the
set
of
characteristics
they
present
to
that
context.
People
frequently
present
different
identities
to
different
contexts,
and
also
frequently
share
an
identity
among
several
contexts.
Cross-context
recognition
is
the
act
of
recognising
that
an
identity
in
one
context
is
the
same
person
as
an
identity
in
another
context
.
Cross-context
recognition
can
at
times
be
appropriate
but
anyone
who
does
it
needs
to
be
careful
not
to
apply
the
norms
of
one
context
in
ways
that
violate
the
norms
around
use
of
information
acquired
in
a
different
context
.
(For
example,
if
you
meet
your
therapist
at
a
cocktail
party,
you
expect
them
to
have
rather
different
discussion
topics
with
you
than
they
usually
would,
and
possibly
even
to
pretend
they
do
not
know
you.)
This
is
particularly
true
for
vulnerable
people
as
recognising
them
in
different
contexts
may
force
their
vulnerability
into
the
open.
In
computer
systems
and
on
the
Web,
an
identity
seen
by
a
particular
website
is
typically
assigned
an
identifier
of
some
type,
which
makes
it
easier
for
an
automated
system
to
store
data
about
that
user.
To
do
this,
user
agents
have
to
make
some
assumptions
about
the
borders
between
contexts
.
By
default,
user
agents
define
a
machine-enforceable
context
or
partition
as:
Even
though
this
is
the
default,
user
agents
are
free
to
restrict
this
context
as
their
users
need.
For
example,
some
user
agents
may
help
their
users
present
different
identities
to
subdivisions
of
a
single
site
.
There
is
disagreement
about
whether
user
agents
may
also
widen
their
machine-enforceable
contexts
.
For
example,
some
user
agents
might
want
to
help
their
users
present
a
single
identity
to
multiple
sites
that
the
user
understands
represent
a
single
party
,
or
to
a
site
across
multiple
installations.
User
agents
should
prevent
their
user
from
being
recognized
across
machine-enforceable
contexts
unless
the
user
intends
to
be
recognized.
This
is
a
"should"
rather
than
a
"must"
because
there
are
many
cases
where
the
user
agent
isn't
powerful
enough
to
prevent
recognition.
For
example
if
two
services
that
a
user
needs
to
use
insist
that
the
user
share
a
difficult-to-forge
piece
of
their
identity
in
order
to
use
the
services,
it's
the
services
behaving
inappropriately
rather
than
the
user
agent
.
If
a
site
includes
multiple
contexts
whose
norms
indicate
that
it's
inappropriate
to
share
data
between
the
contexts,
the
fact
that
those
distinct
contexts
fall
inside
a
single
machine-enforceable
context
doesn't
make
sharing
data
or
recognizing
identities
any
less
inappropriate
.
A
person
's
autonomy
is
their
ability
to
make
decisions
of
their
own
volition,
without
undue
influence
from
other
parties.
People
have
limited
intellectual
resources
and
time
with
which
to
weigh
decisions,
and
by
necessity
rely
on
shortcuts
when
making
decisions.
This
makes
their
privacy
preferences
malleable
[
PRIVACY-BEHAVIOR
]
and
susceptible
to
manipulation
[
DIGITAL-MARKET-MANIPULATION
].
A
person
's
autonomy
is
enhanced
by
a
system
or
device
when
that
system
offers
a
shortcut
that
aligns
more
with
what
that
person
would
have
decided
given
arbitrary
amounts
of
time
and
relatively
unfettered
intellectual
ability;
and
autonomy
is
decreased
when
a
similar
shortcut
goes
against
decisions
made
under
ideal
conditions.
Affordances
and
interactions
that
decrease
autonomy
are
known
as
dark
patterns
.
A
dark
pattern
does
not
have
to
be
intentional,
the
deceptive
effect
is
sufficient
to
define
them
[
DARK-PATTERNS
],
[
DARK-PATTERN-DARK
].
Because
we
are
all
subject
to
motivated
reasoning,
the
design
of
defaults
and
affordances
that
may
impact
user
autonomy
should
be
the
subject
of
independent
scrutiny.
Implementers
are
enjoined
to
be
particularly
cautious
to
avoid
slipping
into
data
paternalism
.
Given
the
sheer
volume
of
potential
data
-related
decisions
in
today's
data
economy,
complete
informational
self-determination
is
impossible.
This
fact,
however,
should
not
be
confused
with
the
contention
that
privacy
is
dead.
Careful
design
of
our
technological
infrastructure
can
ensure
that
users
'
autonomy
as
pertaining
to
their
own
data
is
enhanced
through
appropriate
defaults
and
choice
architectures.
In
the
1970s,
the
Fair
Information
Practices
or
FIPs
were
elaborated
in
support
of
individual
autonomy
in
the
face
of
growing
concerns
with
databases.
The
FIPs
assume
that
there
is
sufficiently
little
data
processing
taking
place
that
any
person
will
be
able
to
carry
out
sufficient
diligence
to
enable
autonomy
in
their
decision-making.
Since
they
entirely
offload
the
privacy
labour
to
users
and
assume
perfect,
unfettered
autonomy
,
the
FIPs
do
not
forbid
specific
types
of
data
processing
but
only
place
them
under
different
procedural
requirements.
Such
an
approach
is
appropriate
for
parties
that
are
processing
data
in
the
1970s.
One
notable
issue
with
procedural
approaches
to
privacy
is
that
they
tend
to
have
the
same
requirements
in
situations
where
the
user
finds
themselves
in
a
significant
asymmetry
of
power
with
a
party
—
for
instance
the
user
of
an
essential
service
provided
by
a
monopolistic
platform
—
and
those
where
user
and
parties
are
very
much
on
equal
footing,
or
even
where
the
user
may
have
greater
power,
as
is
the
case
with
small
businesses
operating
in
a
competitive
environment.
It
further
does
not
consider
cases
in
which
one
party
may
coerce
other
parties
into
facilitating
its
inappropriate
practices,
as
is
often
the
case
with
dominant
players
in
advertising
[
CONSENT-LACKEYS
]
or
in
content
aggregation
[
CAT
].
Reference
to
the
FIPs
survives
to
this
day.
They
are
often
referenced
as
transparency
and
choice
,
which,
in
today's
digital
environment,
is
often
a
strong
indication
that
inappropriate
processing
is
being
described.
Different
procedural
mechanisms
exist
to
enable
people
to
control
the
processing
done
to
their
data
.
Mechanisms
that
increase
the
number
of
purposes
for
which
their
data
is
being
processed
are
referred
to
as
opt-in
or
consent
;
mechanisms
that
decrease
this
number
of
purposes
are
known
as
opt-out
.
When
deployed
thoughtfully,
these
mechanisms
can
enhance
people
's
autonomy
.
Often,
however,
they
are
used
as
a
way
to
avoid
putting
in
the
difficult
work
of
deciding
which
types
of
processing
are
appropriate
and
which
are
not,
offloading
privacy
labour
to
the
user
.
Privacy
regulatory
regimes
are
often
anchored
at
extremes:
either
they
default
to
allowing
only
very
few
strictly
essential
purposes
such
that
many
parties
will
have
to
resort
to
consent
,
habituating
people
to
ignore
legal
prompts
and
incentivising
dark
patterns
,
or,
conversely,
they
default
to
forbidding
only
very
few,
particularly
egregious
purposes
,
such
that
people
will
have
to
perform
the
privacy
labour
to
opt
out
in
every
context
in
order
to
produce
appropriate
processing
.
An
approach
that
is
more
aligned
with
the
expectation
that
the
Web
should
provide
a
trustworthy,
person
-centric
environment
is
to
establish
a
regime
consisting
of
three
privacy
tiers:
When
an
opt-out
mechanism
exists,
it
should
preferably
be
complemented
by
a
global
opt-out
mechanism.
The
function
of
a
global
opt-out
mechanism
is
to
rectify
the
automation
asymmetry
whereby
service
providers
can
automate
data
processing
but
people
have
to
take
manual
action.
A
good
example
of
a
global
opt-out
mechanism
is
the
Global
Privacy
Control
[
GPC
].
Conceptually,
a
global
opt-out
mechanism
is
an
automaton
operating
as
part
of
the
user
agent
,
which
is
to
say
that
it
is
equivalent
to
a
robot
that
would
carry
out
the
user
's
bidding
by
pressing
an
opt-out
button
with
every
interaction
that
the
user
has
with
a
site,
or
more
generally
conveys
an
expression
of
the
user
's
rights
in
a
relevant
jurisdiction.
(For
instance,
under
[
GDPR
],
the
user
may
be
conveying
objections
to
processing
based
on
legitimate
interest
or
the
withdrawal
of
consent
to
specific
purposes
.)
It
should
be
noted
that,
since
a
global
opt-out
signal
is
reaffirmed
automatically
with
every
user
interaction,
it
will
take
precedence
in
terms
of
specificity
over
any
manner
of
blanket
consent
that
a
site
may
obtain,
unless
that
consent
is
directly
attached
to
an
interaction
(eg.
terms
specified
on
a
form
upon
submission).
When
designing
Web
technology,
we
naturally
pay
attention
to
potential
impacts
on
the
person
using
the
Web
through
their
user
agent
.
In
addition
to
potential
individual
harms
we
also
pay
heed
to
collective
effects
that
emerge
from
the
accumulation
of
individual
actions
as
influenced
by
entities
and
the
structure
of
technology.
Note
that
in
evaluating
impact,
we
deliberately
ignore
what
implementers
or
specifiers
may
have
intended
and
only
focus
on
outcomes.
This
framing
is
known
as
POSIWID
,
or
"
the
Purpose
Of
a
System
Is
What
It
Does
".
The
collective
problem
of
privacy
is
known
as
legibility
.
Legibility
concerns
population-level
data
processing
that
may
impact
populations
or
individuals,
including
in
ways
that
people
could
not
control
even
under
the
optimistic
assumptions
of
the
FIPs
.
For
example,
based
on
population-level
analysis,
a
company
may
know
that
site.example
is
predominantly
visited
by
people
of
a
given
race
or
gender,
and
decide
not
to
run
its
job
ads
there.
Visitors
to
that
page
are
implicitly
having
their
data
processed
in
inappropriate
ways,
with
no
way
to
discover
the
discrimination
or
seek
relief
[
DEMOCRATIC-DATA
].
What
we
consider
is
therefore
not
just
the
relation
between
the
people
who
expose
themselves
and
the
entities
that
invite
that
disclosure
[
RELATIONAL-TURN
],
but
also
between
the
people
who
expose
themselves
and
those
who
do
not
but
may
find
themselves
recognised
as
such
indirectly
anyway.
One
key
understanding
here
is
that
such
relations
may
persists
even
when
data
is
permanently
de-identified
.
Legibility
practices
can
be
legitimate
or
illegitimate
depending
on
the
context
and
on
the
norms
that
apply
in
that
context
.
Typically,
a
legibility
practice
may
be
legitimate
if
it
is
managed
through
an
acceptable
process
of
collective
governance
.
For
example,
it
is
often
considered
legitimate
for
a
government,
under
the
control
of
its
citizens,
to
maintain
a
database
of
license
plates
for
the
purpose
of
enforcing
the
rules
of
the
road.
It
would
be
illegitimate
to
observe
the
same
license
plates
near
places
of
worship
to
build
a
database
of
religious
identity.
Legibility
is
often
used
to
order
information
about
the
world.
This
can
notably
create
problems
of
reflexivity
and
of
autonomy
.
Problems
of
reflexivity
occur
when
the
ordering
of
information
about
the
world
used
to
produce
legibility
finds
itself
changing
the
way
in
which
the
world
operates.
This
can
produce
self-reinforcing
loops
that
can
have
deleterious
effects
both
individual
and
collective
[
SEEING-LIKE-A-STATE
].
Issues
of
autonomy
occur
depending
on
the
manner
in
which
legibility
is
implemented.
When
legibility
is
used
to
order
the
world
following
rules
set
by
the
user
or
following
methods
subject
to
public
scrutiny
and
governance
models
with
strong
checks
and
balances
(such
as
a
newspaper's
editorial
decisions),
then
it
will
enhance
user
autonomy
and
tend
to
be
legitimate
.
When
it
is
done
in
the
user
's
stead
and
without
governance
,
it
decreases
user
autonomy
and
tends
to
be
illegitimate
.
Data
governance
refers
to
the
rules
and
processes
for
how
data
is
processed
in
any
given
context
.
How
data
is
governed
describes
who
has
power
to
make
decisions
over
data
and
how
[
DATA-FUTURES-GLOSSARY
].
In
general,
collective
issues
in
data
require
collective
solutions.
The
proper
goal
of
data
governance
at
the
standards-setting
level
is
the
development
of
structural
controls
in
user
agents
and
the
provision
of
institutions
that
can
handle
population-level
problems
in
data
.
Governance
will
often
struggle
to
achieve
its
goals
if
it
works
primarily
by
increasing
individual
control
over
data
.
A
collective
approach
reduces
the
cost
of
control.
Collecting
data
at
large
scales
can
have
significant
pro-social
outcomes.
Problems
tend
to
emerge
when
entities
take
part
in
dual-use
collection
in
which
data
is
processed
for
collective
benefit
but
also
for
self-dealing
purposes
that
may
degrade
welfare.
The
self-dealing
purposes
will
be
justified
as
bankrolling
the
pro-social
outcomes,
which,
absent
collective
oversight,
cannot
be
considered
to
support
claims
to
legitimacy
for
such
legibility
.
It
is
vital
for
standards-setting
organisations
to
establish
not
just
purely
technical
devices
but
techno-social
systems
that
can
govern
data
at
scale.
2.1
People
&
Data
2.2
The
Parties
,
a
legal
entity,
or
can
reasonably
understand
as
a
set
single
"thing"
they're
interacting
with.
Uses
of
legal
entities
that
share
common
owners,
common
controllers,
and
this
document
in
a
group
identity
that
is
readily
evident
particular
domain
are
expected
to
describe
how
the
core
concepts
of
that
domain
combine
into
a
user
without
them
needing
-comprehensible
party
,
and
those
refined
definitions
are
likely
to
consult
additional
material,
typically
through
common
branding.
differ
between
domains.
2.3
Acting
on
Data
2.4
Contexts
and
Privacy
2.5
User
Agents
2.6
Identity
on
the
Web
2.7
User
Control
and
Autonomy
2.8
Opt-in,
Consent,
Opt-out,
Global
Controls
2.9
Collective
Issues
in
Privacy
User agents should attempt to defend their users from a variety of high-level threats or attacker goals, described in this section.
These threats are an extension of the ones discussed by [ RFC6973 ].
These
threats
combine
into
the
particular
concrete
threats
we
want
web
specifications
to
defend
against,
described
in
subsections
here:
Contributes
to
surveillance
,
correlation
,
and
identification
.
Users
of
most
instantiations
of
the
web
platform
expect
that
if
they
visit
a
site
on
one
day,
and
then
visit
again
the
next
day,
the
site
will
be
able
to
recognize
that
they're
the
same
user.
This
allows
sites
to
save
the
user's
preferences,
shopping
carts,
etc.
The
web
platform
offers
many
mechanisms
that
are
either
intended
to
accomplish
this
recognition
or
that
can
be
trivially
used
for
it,
including
cookies
,
A
privacy
harm
only
occurs
if
the
user
wants
to
break
the
association
between
two
visits,
but
the
site
can
still
determine
with
high
probability
that
the
two
visits
came
from
the
same
user.
A
user
might
expect
that
their
two
visits
won't
be
associated
if
they:
This
recognition
is
generally
accomplished
by
either
"supercookies"
or
browser
fingerprinting
.
Supercookies
occur
when
a
browser
stores
data
for
a
site
but
makes
that
data
more
difficult
to
clear
than
other
cookies
or
storage.
Fingerprinting
Guidance
§
Clearing
all
local
state
discusses
how
specifications
can
help
browsers
avoid
this
mistake.
Fingerprinting
consists
of
using
attributes
of
the
user's
browser
and
platform
that
are
consistent
between
the
two
visits
and
probabilistically
unique
to
the
user.
The
attributes
can
be
exposed
as
information
about
the
user's
device
that
is
otherwise
benign
(as
opposed
to
§
3.3
Sensitive
information
disclosure
).
For
example:
See
[
fingerprinting-guidance
]
for
how
to
mitigate
this
threat.
Contributes
to
surveillance
,
correlation
,
and
identification
,
usually
more
significantly
than
§
3.1
Unwanted
same-site
recognition
.
This
occurs
if
a
site
can
determine
with
high
probability
that
a
visit
to
that
site
comes
from
the
same
user
as
another
visit
to
a
different
site.
Contributes
to
correlation
,
identification
,
secondary
use
,
and
disclosure
.
Many
pieces
of
information
about
a
user
could
cause
privacy
harms
if
disclosed.
For
example:
A
particular
piece
of
information
may
have
different
sensitivity
for
different
users.
Language
preferences,
for
example,
might
typically
seem
innocent,
but
also
can
be
an
indicator
of
belonging
to
an
ethnic
minority.
Precise
location
information
can
be
extremely
sensitive
(because
it's
identifying,
because
it
allows
for
in-person
intrusions,
because
it
can
reveal
detailed
information
about
a
person's
life)
but
it
might
also
be
public
and
not
sensitive
at
all,
or
it
might
be
low-enough
granularity
that
it
is
much
less
sensitive
for
many
users.
When
considering
whether
a
class
of
information
is
likely
to
be
sensitive
to
users,
consider
at
least
these
factors:
Issue(16):
This
description
of
what
makes
information
sensitive
still
needs
to
be
refined.
See
intrusion
.
Privacy
harms
don't
always
come
from
a
site
learning
things.
For
example
it
is
intrusive
for
a
site
to
if
the
user
doesn't
intend
for
it
to
do
so.
Contributes
to
misattribution
.
For
example,
a
site
that
sends
SMS
without
the
user's
intent
could
cause
them
to
be
blamed
for
things
they
didn't
intend.
3.1
Unwanted
same-site
recognition
localStorage
,
indexedDB
,
CacheStorage
,
and
other
forms
of
storage.
3.2
Unwanted
cross-site
recognition
3.3
Sensitive
information
disclosure
3.4
Intrusive
behavior
3.5
Powerful
capabilities
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