How do I resolve a "Fatal error: Allowed memory size" error?

Sometimes when using various PHP Content Management Systems; such as WordPress, you may encounter errors stating that you have exceeded the PHP memory limit. The error can look very similar to this:

Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 71 bytes) in /home/user/public_html/index.php on line 744

The above error is very simply to overcome through increasing your PHP memory limit. For information on doing just that, please see the article “Can the PHP configuration be changed?“.