A VPN (virtual private network) encrypts and tunnels all
Internet traffic between yourself and another computer. This
computer might belong to a commercial VPN service, your
organization, or a trusted contact. Because VPN services tunnel
all Internet traffic, they can be used for e-mail, instant
messaging, Voice over IP (VoIP) and any other Internet service
in addition to Web browsing, making everything that travels
through the tunnel unreadable to anyone along the way. If the
tunnel ends outside the area where the Internet is being
restricted, this can be an effective method of circumvention,
since the filtering entity/server sees only encrypted data, and
has no way of knowing what data is passing through the tunnel.
It has the additional effect of making all your different kinds
of traffic look similar to an eavesdropper. Since many
international companies use VPN technology to allow employees
who need access to sensitive financial or other information to
access the companies' computer systems from home or