A browser extension, for example, extends the functionality of a web browser by installing specialized toolbars, adding buttons or links, or offering other helpful capabilities such as pop-up blocking. A browser extension works exactly like any other piece of software, with the exception that some browsers, such as FirefoxTM or Chrome, restrict what it may accomplish.
Add -ON, or Extension
Any third-party software application or script that is added to a program to provide its extra features and abilities is known as a software add-on or extension.
Adobe Flash, for example, allows users to watch films and play games on their browsers. is an excellent example of a software add-on.