To get a better sense of what a REST API is,

let's first talk about how information is transferred on the web.

First, a client requests information from a server using a URL.

Client is a word you'll hear a lot in this course.

It's used to describe an application, often JavaScript running in a web browser

that is requesting information from a server.

The REST in REST API stands for Representational State Transfer, and

it's essentially a set of ideas about how the server should respond to a request

from a client.

A traditional server side application responds with HTML.

A REST API simply responds with data.

It's then up to another application, a front-end application built with

a framework like React or Vue, or a mobile device, or

even a command line tool to format and display the data from the API.

Let's look at a couple of examples of an API.

The Random User Generator, as the name suggests,

generates information about random users.

This could be useful if you need mock data to design and build user interfaces.

Let's take a quick look at the documentation.

Here under the how to use section, we can see that if you make a request to this

URL, randomuser.me/api, you'll receive data about a randomly generated user.

If we make a request to this URL directly from the browser, so

let's copy and paste this into a new tab,

You can see we'll receive a JSON object with a ton of information about a user,

first and last name, location, email, fake login information, and so on.

This is where the flexibility of a REST API comes in.

Once we’ve requested this data, we can do whatever we want with it,

like build the example user interface shown on the front page.

Let’s look at one more example, the GitHub API.

I’ll go to developer.github.com.

From the Docs menu at the top of the page, I'll choose REST API v3.

Don't worry if what you see is different than what's on my screen.

Things are always changing and this is just a demonstration.

Notice here if we click on Current version,

this is the root URL for the GitHub API, api.github.com.

We can add to this URL to receive virtually any information we want as JSON.

On the right side of the screen, I'll click on Users.

And if you look here under Get a single user,

you can see that we can request any single user by tacking on a username.

This colon indicates that this is a placeholder or parameter in the URL.

I can replace :username with any username on GitHub and

get back that user’s information.

So in my browser, I’ll go to

api.github.com/users/treehouse.

And you can see that I get back a bunch of information about the treehouse GitHub

account.

In REST API speak, this is known as requesting a resource,

the GitHub data in this case being the resource.

The URL from which I request the resource is called an endpoint.

By entering this URL into the browser, I'm making a GET request.

And in response,

GitHub's REST API is sending me back the information I requested.

In order to do anything useful with this information,

though, I need a way to make a GET request programmatically with jQuery,

the Fetch API, or a library like Axios.

For information and examples, see the teacher's notes.

As you can see by looking at the menu on the right,

you can do a lot more with the GitHub API.

You can access data about repositories, pull requests, issues, projects,

organizations, pretty much any kind of data you can think of is available for

you to request and display however you'd like.