A Java web component is a server-side object used by a Web-based client (browsers) to interact with J2EE applications. Web components come in two types:
Java Servlet: A server-side Web component used to process requests and construct responses.
JavaServer Pages: Used to create dynamic Web content and server/platform-independent Web-based applications.
Techopedia explains Web Component
A Web browser interacts with a J2EE application via the Java Servlet and JavaServer Pages Web components. However, Web component development and execution processes differ from typical stand-alone Java classes.
The Web container - the environment where Web components are executed - also provides services required for execution. If a Web component is executed by a Web container, the component must first be deployed in a Web container.
There are four basic steps involved in Web component development and execution:
Writing Web component code. A deployment descriptor also may be included in the code.
Packaging the Web component, along with the resources referenced in the code such as images and videos.
Installing the Web component in the Web container.
Accessing the link that refers to the Web component.
This definition was written in the context of Java