Variables keep a value for future usage.
This value stored in variable can be changed.
<?php $a = 1; /* w w w . jav a2s . c om*/ $b = 2; $c = $a + $b; echo $c; // 3 ?>
Here, we have three variables: $a has value 1, $b has 2, and $c contains the sum of $a and $b, hence, $c equals 3.