Autoconf is an extensible package of M4 macros that produce shell scripts to automatically configure software source code packages. These scripts can adapt the packages to many kinds of UNIX-like systems without manual user intervention. Autoconf creates a configuration script for a package from a template file that lists the operating system features that the package can use, in the form of M4 macro calls.

Producing configuration scripts using Autoconf requires GNU M4. You should install GNU M4 (version 1.4.7 or later) before configuring Autoconf, so that Autoconf's configure script can find it. The configuration scripts produced by Autoconf are self-contained, so their users do not need to have Autoconf (or GNU M4).

For more information, see the original page: http://www.gnu.org/software/autoconf/