Wikipedia
TortoiseCVS is a CVS client for Microsoft Windows released under the GNU General Public License. Unlike most CVS tools, it includes itself in Windows' shell by adding entries in the contextual menu of the file explorer, therefore it does not run in its own window. Moreover, it adds icons onto files and directories controlled by CVS, giving additional information to the user without having to run a full-scale stand-alone application.
The name is a pun on the word shell. The tortoise in the logo is called Charlie Vernon Smythe (CVS).
The project was started by Francis Irving when he was employed by Creature Labs to provide a better interface to CVS for his colleagues. Some of the code was derived from WinCVS and CVSNT. The first release was 4 August 2000.