Winning entries are awarded with a category, such as "Worst Abuse of the C preprocessor" or "Most Erratic Behavior", and then announced on the official IOCCC website.

The IOCCC was started by Landon Curt Noll and Larry Bassel in 1984 while employed at National Semiconductor's Genix porting group.

The idea for the contest came after they compared notes with each other about some poorly written code that they had to fix, notably the Bourne shell, which used macros to emulate ALGOL 68 syntax, and a buggy version of finger for BSD.

[11] In the effort to take obfuscation to its extremes, contestants have produced programs which skirt around the edges of C standards, or result in constructs which trigger rarely used code path combinations in compilers.

Within the code size limit of only a few kilobytes, contestants have managed to do complicated things – a 2004 winner turned out an operating system.

The author claims that it is the world's smallest chess program written in C. The source code for Toledo Nanochess and other engines is available.

In 2014 the 1 kilobyte barrier was broken by Super Micro Chess[17] – a derivative of Micro-Max – totaling 760 characters (spaces and newlines included).

[20]) Another example is the following flight simulator, the winner of the 1998 IOCCC,[21] as listed and described in Calculated Bets: Computers, Gambling, and Mathematical Modeling to Win (2001)[22] and shown below: This program needs the following command line on a Linux system to be compiled:[21] In order to run the binary file (banks) it has to be supplied with a .sc scenery file via stdin input:[21] Below is a 2011 entry which downsamples PGM, PPM images and ASCII art (of Akari from YuruYuri) by Don, Yang:[23]