This page shows how to include one file into another using PHP's built-in include() function.

There are a few variations of including one file within another:

• include() - includes one file within another if that file exists, even if there are duplicate include statements
• include_once() - includes one file within another if that file exists, but ignores duplicate include statements
• require() - includes one file within another even if there are duplicate require statements, but throws a fatal error if that file does not exist
• require_once() - includes one file within another and throws a fatal error if that file does not exist, but ignores duplicate require statements