Sams Teach Yourself PHP in 24 Hours, Third Edition

Superglobal Variables

Before you actually build a form and use it to acquire data, we need to make a small detour and look at superglobal variables. We first met global variables in Hour 6, “Functions.” A global variable is any variable declared at the “top level” of a script—that is, declared outside a function. Superglobal variables are arrays built in to PHP. They are populated for you automatically with useful elements, and they are available in any scope. You can access a superglobal array within a function or method without using the global keyword. We will encounter superglobal variables throughout the rest of this book. Table 10.1 provides a summary.

Table 10.1. PHP Superglobal Arrays

Array	Description
$_COOKIE	Contains keys and values set ...