Squid is a caching proxy for the Web supporting HTTP, HTTPS, FTP, and
more. It reduces bandwidth and improves response times by caching and
reusing frequently-requested web pages. Squid has extensive access
controls and makes a great server accelerator.

Squid 3.0 represents a major rewrite of Squid and has a number of new
features.

The most important of these are: - Code converted to C++, with
significant internal restructuring and rewrites.

- ICAP implementation (RFC 3507 and www.icap-forum.org)

- Edge Side Includes (ESI) implementation (www.esi.org)

Most user-facing changes are reflected in squid.conf.