Autoconf is a tool used in software development to create configuration scripts that automatically adapt software packages to various Unix-like systems. It simplifies the process of preparing software for installation by checking for system features, libraries, and dependencies, ensuring compatibility across different environments. By generating a configure script, Autoconf allows developers to specify how their software should be built and installed on different systems. This helps streamline the installation process for users, as they can run the script to configure the software according to their specific system settings without needing to modify the source code directly.