Bulletin boards commonly accept uploaded files from their users. The BBS software would prompt the user to supply a description for the uploaded file, but these descriptions were often less than useful. BBS system operators spent many hours going over the upload descriptions correcting and editing the descriptions. The FILE_ID.DIZ inclusion in archives was designed to address this problem.
FILE_ID stands for "file identification". DIZ stands for Description In Zipfile. In addition, when written in lowercase and rotated 180 degrees, the 'diz' file extension looks like 'zip'.
Clark Development and the Association of Shareware Professionals supported the idea of this becoming a standard for file descriptions. Clark rewrote the PCBDescribe program and included it with their PCBoard BBS software. The ASP urged their members to use this description file format in their distributions. Michael Leavitt, an employee of Clark Development, released the file specification and his PCBDescribe program source code to the public domain and urged other BBS software companies to support the DIZ file.
Traditionally, a FILE_ID.DIZ should be "up to 10 lines of text, each line being no more than 45 characters long." according to the specification v1.9. 
The concept of DIZ files was to allow a concise description of uploaded files to be automatically applied - advertisements and "high ASCII" artwork were specifically prohibited.
Even after the decline of the dial-up bulletin board system, FILE_ID.DIZ files are still utilized by the warez scene in their releases of pirated software. They are commonly bundled as part of the complete packaging by pirate groups, and indicate the number of disks, and other basic information. Along with the NFO file, it's essential to the release.
- .nfo — another standard for description files
- Portable Application Description — a newer and more verbose alternative
- Standard (warez)
- DESC.SDI — a similar filename that had fairly wide support, including PCBoard. It tended to be limited to a single line (smaller than a FILE_ID.DIZ file).
- Fong, B. C.; Doyle, D. J. (1995). "Renal function tests for windows — a model for the development and distribution of medical software on the Internet". International Journal of Bio-Medical Computing 40 (1): 69–75. doi:10.1016/0020-7101(95)01126-Y. PMID 8557407. "Short ANSI text file (31 characters wide) often automatically extracted by Bulletin Board Service programs."
- White, Ron (July 2001). "Mystery Files". Ziff Davis Smart Business 14 (7): p100. ISSN 1535-9891. "DIZ stands for Description in Zip."
- Craig, P.; Honick, R.; Burnett, M. (2005). "The Release". Software Piracy Exposed. p. 95. doi:10.1016/B978-193226698-6/50030-1. ISBN 978-1-93-226698-6.
- FILE_ID.DIZ Specification v1.9 by Richard Holler.