The definition of open source software was written to be almost identical to the free software definition.

These freedoms are formally described in The Free Software Definition, first published in February 1986.

The first libre definition was the free software definition published by the Free Software Foundation in 1986.

In these contexts, libre encompasses the essential freedoms defined in the free software definition, and is used to describe works which may be used, modified, copied and shared without permission from the copyright holder.

The free/libre knowledge definition above was inspired by the Free Software definition and by a posting on Jimmy Wales's blog "Free Knowledge requires Free Software and Free File Formats".

This was viewed as not compliant with the open source principle by the Open Source Initiative and the free software definition by Free Software Foundation because, while the source was available, it did not allow the redistribution of modified versions.