What are the differences between mod_php and cgi php script?

Question

What are the differences between mod_php and cgi php script?

I mean, why it's better (is it?) to use mod_php instead simple php scripts, running them as CGIs?

Thanks

Answer 1

When using CGI : a PHP process is launched by Apache, and it is that PHP process that interprets PHP code -- not Apache itself.

In theory, a distinct PHP process has to be created for each request -- which makes things slower : Apache has more work to do to answer a request.
(Well, as pointed out by @AlReece45 in a comment, this can be made better using FastCGI)

When using PHP as an Apache module (mod_php, or mod_php5), the PHP interpreter is kind of "embedded" inside the Apache process : there is no external PHP process.

Which means :

• No forking to answer a request (faster)
• Better communication between Apache and PHP

Generally speaking, I would say that mod_php is the solution that's used the most.