An application is a software program designed to perform a specific task or group of functions. There are many applications, ranging from simple tools to complex systems. Some common examples include word processors, web browsers, and email clients.
Applications are typically developed for a specific platform, such as Linux, Windows, or macOS. This means they can only be used on devices supporting that platform. So, for example, an application designed for Windows will not work on a Mac unless it has explicitly been ported to the Mac platform.
Most applications are released as commercial products and must be purchased by the user to be used. However, there are also many open-source applications available for free online. These can be downloaded and used by anyone who wishes to do so without charge.