What is a REST API?

To get a better sense of what a REST API is, 0:00 let's first talk about how information is transferred on the web. 0:02 First, a client requests information from a server using a URL. 0:05 Client is a word you'll hear a lot in this course. 0:09 It's used to describe an application, often JavaScript running in a web browser 0:12 that is requesting information from a server. 0:16 The REST in REST API stands for Representational State Transfer, and 0:18 it's essentially a set of ideas about how the server should respond to a request 0:23 from a client. 0:27 A traditional server side application responds with HTML. 0:28 A REST API simply responds with data. 0:31 It's then up to another application, a front-end application built with 0:34 a framework like React or Vue, or a mobile device, or 0:39 even a command line tool to format and display the data from the API. 0:42 Let's look at a couple of examples of an API. 0:47 The Random User Generator, as the name suggests, 0:49 generates information about random users. 0:51 This could be useful if you need mock data to design and build user interfaces. 0:54 Let's take a quick look at the documentation. 0:58 Here under the how to use section, we can see that if you make a request to this 1:02 URL, randomuser.me/api, you'll receive data about a randomly generated user. 1:08 If we make a request to this URL directly from the browser, so 1:14 let's copy and paste this into a new tab, 1:18 You can see we'll receive a JSON object with a ton of information about a user, 1:22 first and last name, location, email, fake login information, and so on. 1:27 This is where the flexibility of a REST API comes in. 1:32 Once we’ve requested this data, we can do whatever we want with it, 1:35 like build the example user interface shown on the front page. 1:40 Let’s look at one more example, the GitHub API. 1:44 I’ll go to developer.github.com. 1:47 From the Docs menu at the top of the page, I'll choose REST API v3. 1:53 Don't worry if what you see is different than what's on my screen. 1:58 Things are always changing and this is just a demonstration. 2:01 Notice here if we click on Current version, 2:04 this is the root URL for the GitHub API, api.github.com. 2:08 We can add to this URL to receive virtually any information we want as JSON. 2:13 On the right side of the screen, I'll click on Users. 2:18 And if you look here under Get a single user, 2:21 you can see that we can request any single user by tacking on a username. 2:24 This colon indicates that this is a placeholder or parameter in the URL. 2:29 I can replace :username with any username on GitHub and 2:34 get back that user’s information. 2:37 So in my browser, I’ll go to 2:40 api.github.com/users/treehouse. 2:43 And you can see that I get back a bunch of information about the treehouse GitHub 2:49 account. 2:53 In REST API speak, this is known as requesting a resource, 2:53 the GitHub data in this case being the resource. 2:57 The URL from which I request the resource is called an endpoint. 3:00 By entering this URL into the browser, I'm making a GET request. 3:04 And in response, 3:08 GitHub's REST API is sending me back the information I requested. 3:09 In order to do anything useful with this information, 3:13 though, I need a way to make a GET request programmatically with jQuery, 3:17 the Fetch API, or a library like Axios. 3:22 For information and examples, see the teacher's notes. 3:24 As you can see by looking at the menu on the right, 3:27 you can do a lot more with the GitHub API. 3:30 You can access data about repositories, pull requests, issues, projects, 3:32 organizations, pretty much any kind of data you can think of is available for 3:37 you to request and display however you'd like. 3:42