An alternate website or datacenter that contains the same information as the original. Mirror sites are set up for backup and disaster recovery as well as to balance the traffic load for numerous download requests on the Web. Such "download mirrors" are often placed in different locations throughout the Internet.
Hopefully Not a Real Mirror
It is common to use the term mirror to refer to an exact copy of data; however, a real mirror reverses characters. Stand in front of a mirror with some text on a T-shirt, and you find the letters reversed. Thus a mirror image of data is a technical misnomer, but all is fair in love and technology. See
RAID,
disaster recovery and
mirror folder.