A web extension is a software module that adds functionality to a web browser. It's a type of browser extension that can modify or enhance the functionality of a web browser by adding new features, tools, and user interfaces.
Examples of common web extensions include ad-blockers, password managers, and social media integrations. They can be installed directly from the browser's extension store and typically work across multiple operating systems and browser platforms. In addition, many popular web browsers, such as Google Chrome, Mozilla Firefox, and Microsoft Edge, support the development and use of web extensions.