What some people above were trying to imply...
PHP Includes are some of the simplest functions in PHP, and work very similarly to iFrames, but can be controlled in many different ways that you will find out as you look into PHP.
Includes are not necissarily faster than frames, such as pages executing large queries or loading lots of content. Although you could steer away from that, an iFrame alows your body to load below the iFrame script in the source, before the iframe itself has been loaded.
Note, if you want to have scroll bars, and you think you need iFrames to have them, look into CSS and take a look at the Overflow attribute, which you can assign to a div along with dimensions of an iFrame look alike.
PHP? Hard to Learn? With P2L it gets a whole lot easier

My advice is that you start off slow, and DONT START WITH REGEX...AHHHH!
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