Add-on may refer to the following:
1. A software add-on is any third-party software program or script that is added to a program to give it additional features and abilities. Adobe Flash, which allows users to watch videos or play games within an Internet browser, is a great example of a software add-on.
2. When referring to hardware, an add-on is any component that enhances the capabilities or performance of your computer. For example, additional RAM, a new CPU, or a faster video card could all be considered add-ons.