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==Scope==

Scope refers to what can actually modify a variable, e.g:
<syntaxhighlight lang="php">
<?php
$var = 1;
require 'another_page.php';
?>
</syntaxhighlight>

The page 'another_page.php' has full access to the variable 'var'.
<syntaxhighlight lang="php">
<?php
$var = 'Test';
function test()
{
 echo $var;
}
test();
?>
</syntaxhighlight>
OUTPUT->
The above would output nothing, since functions have their own scope, variables outside that scope would not be available.

===Globals===

You can force functions to access other variables by using the global keyword, e.g:
<syntaxhighlight lang="php">
<?php
$var = 'Test';
function test()
{
 global $var;
 echo $var;
}
test();
?>
</syntaxhighlight>

Would output: Test

Or you can use the $GLOBALS array, like this:
<syntaxhighlight lang="php">
<?php
$GLOBALS['var'] = 'Test';
function test()
{
 echo $GLOBALS['var'];
}
test();
?>
</syntaxhighlight>

===Static Variables===

Static variables exist within a function and are saved after the function executes, e.g:
<syntaxhighlight lang="php">
<?php
function increment()
{
 static $a = 0;
 echo $a;
 $a++;
}
increment(); // 0
increment(); // 1
increment(); // 2
increment(); // 3
?>
</syntaxhighlight>

If the variable 'a' was not static, it would echo 0 each time.