Writing

Writing is the action to replace a value in a data container with another one. It does not need to be read. The value is simply changed.

Writing happens when a value is being assigned a new value, used with some operators such as ++ or --.

This operation is usually the counterpart of reading. It may also happen at the same time.

<?php

$x = 1; // writing 1

++$x; // reading 1 and writing 2

echo $x; // reading 2

?>

Related : Reading