Short answer: everything
Long answer: everything
Gray area: it depends!
Essentially an archive is established to preserve memory; of an institution, a nation, or even of a person. This is done by collecting, arranging, preserving, cataloguing, and organizing materials relevant to that entity's existence. And my materials, I mean ANYTHING. Fashion designers have archives, the U.S. Government, of course, has one (actually, a few) famous personalities tend to have their papers and artifacts housed, really anyone or anything can have an archive.
The size of a ZIP archive, as well as the size of any single file within a ZIP archive, is limited to 2 GB.
in the archive
JAR files (Java ARchive) allows aggregating many files into one, it is usually used to hold Java classes in a library. i.e. Math.jarWAR files (Web Application aRchive) stores XML, java classes, and JavaServer pages for Web Application purposes.EAR files (Enterprise ARchive) combines JAR and WAR files to make a combined archive for Enterprise Applications.
The Archive-It service of the Internet Archive Wayback Machine is something that allows different institutions to preserve their own web archive of digital content. It is designed to fit the needs of many organizations.
Pandora Archive was created in 1996.
Archive Alive was created in 1997.
The Dalkey Archive was created in 1964.
Archive Fever was created in 1995.
Trunk Archive was created in 2004.
MySQL Archive was created in 2004.
Datasheet Archive was created in 1993.
Archive Cardiacs was created in 1977.