An applet is a small computer program that performs a specific task and is typically embedded within another larger app or software platform. Applets are often used in enterprise software, where they enable users to quickly access features without having to load a full app or switch windows. They can also be used for customizing the look and feel of desktop applications, providing the ability to personalize how the app looks and feels. In web development, applets allow developers to add interactive elements and animations to websites without needing too much additional coding.

The term "applet" is frequently used to refer to a Java applet, which is a program written in the Java programming language that is designed to be placed on a web page. Java applets were used to provide interactive features to web applications that historically could not be provided by HTML alone. They could capture mouse input and also had controls like buttons or check boxes. In response to the user action, an applet could change the provided graphic content. This made applets well suited for demonstration, visualization, and teaching.

Applets are not full-featured application programs and are intended to be easily accessible. They are typical examples of transient and auxiliary applications that do not monopolize the users attention. An applet can be a fully functional Java application because it has the entire Java API at its disposal. Every applet is an extension of the java.applet.Applet class, which provides methods that a derived Applet class may call to obtain information and services from the browser context.

In summary, an applet is a small program that performs a specific task and is typically embedded within another larger app or software platform. It can be used to add interactive elements and animations to websites, and Java applets were historically used to provide interactive features to web applications that HTML alone could not provide.