In fact, this client/server relationship is a prerequisite of a set of principles called REST (or Representational State Transfer). This sounds kind of scary, but it's super easy—let's walk through it together.
Remember how we said HTTP involves sending hypertext (text with links)? Whenever you navigate through a site by clicking links, you're making a state transition, which brings you to the next page (representing the next state of the application). That's it!
By following this simple model of clicking from page to page, you're starting to follow REST principles. When something follows REST principles, we say that thing is RESTful. We'll cover these principles in the next exercise.