GNU nano is an open source, curses-based text editor for Unix systems. It is a clone of [tag:pico], the proprietary Pine e-mail client editor.
Nano is a simple, small, lightweight text editor for unix written in c. It was created in 1999 under the name TIP ("this isn't pico"). It was renamed to avoid conflit with the tip
command in 2000 and officially joined the GNU project in 2001.
Nowadays, nano supports interaction through mouse, syntax highlight, regex-based search, customization of key bindings and (experimental) undo/redo support. More about it can be read in its homepage.