This document provides an introduction to autotools. It discusses the purpose of autotools in making code portable and easy to install. It then describes the relationships between various autotools tools like autoconf, automake, autoreconf. It provides examples of configure.in and Makefile.am files. Key sections are on generating configure scripts from configure.in, generating Makefiles from Makefile.am, and the directory structure and files involved in the build system. Usage of common autoconf macros are demonstrated.