These are PHP handlers, this is what executes your php pages.
suPHP runs as a CGI module and its major benefits are stronger security and easy permissions.
DSO runs as an Apache module, DSO also referred to as mod_php, is one of the oldest PHP handlers and its major benefits are speed and the ability to use opcode caching.
FCGI also referred to as mod_fcgid, is one of the newest PHP handlers and its major benefits are CPU performance and caching
You only need to select one php handler, I recommend suPHP as the php script is executed as the owner(user) rather than the web server.
