Vim (/vɪm/; a contraction of Vi IMproved) is a clone, with additions, of Bill Joy's vi text editor program for Unix. Vim's author, Bram Moolenaar, based it on the source code for a port of the Stevie editor to the Amiga and released a version to the public in 1991. Vim is designed for use both from a command-line interface and as a standalone application in a graphical user interface. Vim is free and open-source software and is released under a license that includes some charityware clauses, encouraging users who enjoy the software to consider donating to children in Uganda. The license is compatible with the GNU General Public License through a special clause allowing distribution of modified copies "under the GNU GPL version 2 or any later version".