php5 - I want to use includes for my menus that will be on every page so that I don't always

I want to use includes for my menus that will be on every page so that I don't always have to go on every single page to make changes.

Which extension should i use :
.php or .shtml ?

Which will run faster?

which to use would depend on what your server supports. As far as which is faster, they both would take milliseconds to run so I doubt that would make much of a difference. more than likely though, you would use php if you are including the file in a php script.

i would use php. even if you dont need any scripting power in the include today, you may in the future.