fcgi php

[daktau]

Hello,
Can anyone explain to me what fcgi means in terms of php? If I check my phpinfo file it tells me that the php is set up as:

Server API CGI

.....so does this mean that it is or it isn't fcgi?
Is there a difference between the 2?

How does one go about resetting how php runs and how will this affect the site?

cheers,
George