metasploit-framework/modules/README.md

This is the folder where all of Metasploit's modules live. These modules are scripts in Ruby that interface with Metasploit itself to perform some specific task. There are various types of modules, such as exploit modules to exploit a vulnerability and gain a shell, auxiliary to perform a non-shell gaining activity, payloads for Metasploit's various payloads (which are also modules), and post for post exploitation modules.