Introduction to the Back End


The “frontend” denotes the interface that a web user interacts with - what they see (and hear) when using the web. The three languages of the frontend are fairly standardized: HTML for markup, CSS for presentation, and JavaScript for scripting.

The “backend”, meanwhile, denotes all that goes on “behind the scenes” on web servers to make the user experience possible. In contrast to front-end development, you can run pretty much any language you want to on your server since it doesn’t rely on your user’s browser understanding what’s going on. All the browser cares about is whether you’ve sent it properly formatted HTML, CSS and JavaScript files (and other assets like images). That’s led to a whole lot of different choices for back-end languages. As long as it can take in an HTTP request and spit out some HTML, you can probably put it on a server somehow.

That said, some languages are more popular and practical than others. If you’re running your own server, you have a ton of flexibility but plenty of headaches. If you’re using the cloud (which we will be doing later), you may be restricted to those languages that your cloud provider has installed on their platform… It doesn’t do you much good if the servers you’re “borrowing” from can’t understand your code!

Some of the most popular server-side languages are PHP, ASP.NET, Ruby, Python and Java (not to be confused with JavaScript). Just as I can say “Which way to the nearest pub?” in Swedish, French, Italian, English, and Bad English, so too can all of those languages perform almost exactly the same functions, just using different syntax.

As we covered back in the Installations section, the front-end languages live in the browser so there are no extra installations required. For the reasons listed above, the back-end languages do require you to install them on your computer in order to get them running. NodeJS has already been installed as it is required in the JavaScript section of Foundations. Ruby and Rails are installed in their own respective sections as they aren’t required until then.

Learning Outcomes

  • What is the difference between front-end and back-end development?
  • Why are we required to install back-end languages on our computer (besides to run them)?


  1. Check out this blog post on backend vs frontend programming for a quick refresher on the difference between the two.
  2. A good and short overview of the backend.
  3. A much more detailed and thorough explanation of the various aspects of the backend is provided by Codecademy, including a step-by-step breakdown of what happens in the backend when a browser makes a request to a server.

Knowledge Check

This section contains questions for you to check your understanding of this lesson. If you’re having trouble answering the questions below on your own, review the material above to find the answer.

Improve this lesson on GitHub

Have a question?

Chat with our friendly Odin community in our Discord chatrooms!

Open Discord