MakeIndex is a computer program which provides a sorted index

Index (publishing)

An index is a list of words or phrases and associated pointers to where useful material relating to that heading can be found in a document...

 from unsorted raw data. MakeIndex can process raw data output by various programs, however, it is generally used with LaTeX

LaTeX

LaTeX is a document markup language and document preparation system for the TeX typesetting program. Within the typesetting system, its name is styled as . The term LaTeX refers only to the language in which documents are written, not to the editor used to write those documents. In order to...

 and troff

Troff

troff is a document processing system developed by AT&T for the Unix operating system.-History:troff can trace its origins back to a text formatting program called RUNOFF, written by Jerome H. Saltzer for MIT's CTSS operating system in the mid-1960s...

.

MakeIndex was written around the year 1986 by Pehong Chen in the C programming language

C (programming language)

C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....

 and is free software

Free software

Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...

. Six pages of documentation titled "MakeIndex: An Index Processor for LaTeX" by Leslie Lamport are available on the web and dated "17 February 1987."