The developer specifies the desired behaviour of the configure script by writing a list of instructions in the GNU m4 language in a file called "configure.ac".

Autoconf was begun in the summer of 1991 by David Mackenzie to support his work at the Free Software Foundation.

In the subsequent years it grew to include enhancements from a variety of authors and became the most widely used build configuration system for writing portable free or open-source software.

[2] Autoconf generates a configure script based on the contents of a configure.ac file, which characterizes a particular body of source code.

There is some criticism that states that Autoconf uses dated technologies, has a lot of legacy restrictions, and complicates simple scenarios unnecessarily for the author of configure.ac scripts.