Metasploit is an open source exploitation framework that acts as a tool for developing and executing exploit code against a remote target machine
The Metasploit Framework is an open-source project owned/sponsored by Rapid7 for vulnerability assessment, exploitation development, penetration testing, and many other computer and network security-related tasks.
Since version 3 of the Framework, Metasploit has been written primarily in Ruby. Version 2 and older were written in Perl. The various payloads, stagers, and shellcodes are primarily written in C, assembly, and Java.