On the Internet 'Mirror' refers to copies of the same location on other web servers in order to help distribute something under stress. This can include the attacks, the Slashdot Effect, litigation, or friendly community support. Files distributed on peer-to-peer networks such as BitTorrent or Kazaa are not considered mirrors.
The term "Mirror" of course comes from the way an image's exact duplicate appears in a reflective surface but a mirror may not contain the exact same file, for which MD5 hashes are sometimes distributed.
- Publisized use of Mirrors (testing the legality of simply linking to a file and not actually hosting it) was the 2600 DeCSS-linking case.
- Google Cache - a free mirroring service from Google to help keep Web pages at least partially alive in the event of a failure. It is sometimes referenced instead of the original page due to the robustness of Google's servers.
- www.archive.org - a free mirroring service which also stores Archived copies of web pages
- Mirrordot.com is trying to combat the Slashdot Effect
- Getleft A free Web site "grabber" that downloads the entirety of a remote Web site for offline viewing or for mirroring.
- Google Cache.