Squid is a high-performance proxy caching server for Web clients,
supporting FTP, gopher, and HTTP data objects. Unlike traditional
caching software, Squid handles all requests in a single,
non-blocking, I/O-driven process. Squid keeps meta data and especially
hot objects cached in RAM, caches DNS lookups, supports non-blocking
DNS lookups, and implements negative caching of failed requests.
Squid consists of a main server program squid, a Domain Name System
lookup program (dnsserver), a program for retrieving FTP data
(ftpget), and some management and client tools.