Consider an analogy of a web application as a planet. Astronauts travel to the planet to explore its surface, similar to how someone uses a web browser to explore or browse a web application. Although we only see the surface of a planet, a lot is going on under the surface. You can imagine the whole planet as a web server with many things going on under the surface of the web server, yet all we can usually see is the surface of web pages or apps. We will now explore the various components that make up a web application.