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<title>Tor: Overview</title>
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<h2>Tor: Overview</h2>
<h3>Traffic analysis</h3>
<p>
Traffic analysis can be used to infer who is talking to whom over a
public network. For example, Internet packets have a header used for
routing, and a payload that carries the data. The header, which must be
visible to the network (and to observers of the network), reveals the
source and destination of the packet. Even if the header were obscured
in some way, the packet could still be tracked as it moves through the
network. Encrypting the payload is similarly ineffective, because the
routing information is all an observer needs.
</p>
<p>
Knowing the source and destination of your Internet traffic allows
somebody to track your behavior and interests, impacting your checkbook or
even threatening your job or physical safety.
</p>
<p>
Individuals, corporations, and governments all have an interest in
traffic analysis protection. Individuals want to protect themselves and
their family members from remote websites, or connect to resources such
as news sites or instant messaging services that are blocked locally.
User groups such as the German "Diabetes People" organization recommend
Tor for their members' online privacy and security. Activist groups such
