# 3.1 next pages and links - each next page exports a react component >A React component is a building block for building user interfaces using the React library. A component in React is a modular, reusable piece of code that represents a portion of the UI. A component can be a small part of a larger UI or can represent the entire UI itself. Components in React can be thought of as custom HTML tags that you can use to encapsulate specific pieces of functionality. - as we mentioned before, the file/folder structure in your `src/pages` directory is going to be turned in to the structure of your site. It's somewhat important to realize that Next is doing this for you and that it doesn't happen automatically in React apps, but we won't be learning about [react routing](https://hygraph.com/blog/routing-in-react) in this tutorial. It's actually pretty complicated, and in the end a lot of what you're trying to do is to rebuild what Next does out of the box. So mainly be thankful that Next handles this for you and then move on :) -