This document discusses collaboration between free and open source software projects. It describes how individuals and organizations have built bridges between projects through both technical and non-technical cooperation on common problems and shared values. Some examples of cooperation include federator projects in the 1990s, inter-project cooperation since the 1980s, and various free software events since 2000. In 2005, the Freedesktop.org foundations list was started to facilitate cooperation, and now has over 50 member organizations and around 140 individual members.