We all know that Joomla is a fantastic CMS for building professional websites. The JED (Joomla Extension Directory) is full of components, modules and plugins that can add almost any type of functionality to any Joomla site. That's great and all but what if you find a component or module that gives the functionality needed but the output and layout is not exactly what you want? A big mistake that some developers and webmasters make is going in and editing the core code of an extension. Joomla makes it easy by allowing overrides.
What is an Override?
An override is a copy of an extensions layout/template file that is placed in your Joomla template directory. You can then customize it to your liking. The difference with doing this as oppose to just editing the file in the extension directory is that when you upgrade Joomla or the extension, your changes will not be replaced with the new versions. Joomla knows to look in the overridden file first, then the actual extensions file.