Seamonkey used to be simply be known as "Mozilla" or "Mozilla Application Suite", and was the original browser by Mozilla before they decided to spin off the code into the "Phoenix" and "Thunderbird" projects. Originally the plan was that Mozilla was a browser for developers and that consumers would use Netscape. However AOL laid off the Netscape developers in 2003 and focus was switched to making Phoenix, which was then called Firebird the main product of the Mozilla project, and it become known as Firefox in 2004. I was around for the original 1.0 releases of Firefox and Mozilla, and after it was clear that Firefox was more popular than the Mozilla Application Suite it was spun off into the Seamonkey project, taking the name from the original codename used in the development of the browser. In recent years, the legacy code of Seamonkey means that its rendering engine hasn't kept up with Firefox, meaning that most modern sites don't work with it anymore, but it is an interesting historical browser who's user interface hasn't changed much since the 2000s, compared to Firefox which changes its user interface regularly.