Metalink is an open standard that harnesses the speed and power of peer to peer networking, FTP, and HTTP within a single click. For increased convenience, it stores the multiple download locations for a file (FTP/HTTP/P2P) in a single metafile with the extension .metalink. This provides reliability in case one or many servers fail. Metalinks can also contain checksums to repair downloads and digital signatures, along with other information. Also see the Wikipedia article on Metalink.
Wubi, the Windows-based Ubuntu installer, uses Metalinks to download ISO files.
Software to use Metalink
Under Ubuntu and its derivatives, you can use any method to install the aria2 package, then from the terminal, issue
such as, for example,
to download the Desktop CD of Ubuntu 11.04.
On Kubuntu, you can additionally use any method to install the kget package, which provides a graphical interface to Metalink downloads.
Under Mac OS X you can also manually download aria2 and do the same.
Ubuntu in Metalink format
Metalinks for all Ubuntu, Kubuntu and Edubuntu releases are available from http://releases.ubuntu.com/
11.10 (Oneiric Ocelot)
11.04 (Natty Narwhal)
10.10 (Maverick Meerkat)
Ubuntu 10.04 (Lucid Lynx)