Instructions include, require and readfile
There are two instructions that allow you to switch to the code contents of another file also contains PHP code. Both of these instructions is given one parameter – the name of the file to include in the code (it can be the path to a file located on another web server). The difference between them is how to enable these files to the code. For instructions “require” the files are attached to the code before parsing, in every place where there is an instruction “require”.