PHP is an incredibly rich language, as I hope you have come to see by reading this far - there are extensions available to perform all sorts of popular operations with external libraries that really help add power to your script without much effort.
So, why would anyone want to write their own extension? We'll be answering that question in this chapter, as well as designing and producing from scratch a new extension for PHP. Note that this entire chapter requires you have a compiler to hand so that you can compile your extension. You need to be able to compile PHP - usually this requires a Unix operating system, but if you have Windows and a Windows compiler, or Cygwin, that will do also. Otherwise, while the information here might be interesting, you will not be able to make use of it unless you can compile PHP.