RB is a file extension used by text files that store code written in Ruby programming language. Ruby is a very robust and user-friendly programming language; it is an object-oriented and dynamically-typed language, and its syntax resembles that of CLU or Python programming language.

RB files aren’t compiled as Ruby is an interpreted language. To run code in RB files a Ruby interpreted must be installed on the system. RB files can be edited using any standard text editor tool, but typically for editing such files more specialized editors are used which support such functions as syntax highlightning, code auto-completion, etc.