You may have heard the terms “back end” and “front end” with respect to web development languages. Some may find them confusing, but there is not too much mystery to it at all.

In the most basic terms, the moniker says it all: a back language runs on the server and does all its work before the page gets to you. By the time you see the web page, any back end  technology that was used to construct and then serve up the page is no longer involved. Conversely, a front end language operates on the client side. It works in your browser and does not do anything until the page and its associated assets comes over the wire.

Back End Programming Language

An example of a back end language is PHP, which is a scripting language. When a user requests a PHP page, the server parses the PHP code, which in most cases results in dynamically created HTML. A PHP page can simply contain HTML. It is not required to include any scripting code at all, but any code that is in the page will be parsed.  Consequently, the web page viewer never sees one line of PHP code. Assuming that the web server administrator has configured the server correctly, it will surely never show you the actual PHP code.  This is because the web server parses the PHP and then generates the page. This results in HTML. Although, a web developer can use PHP to serve up any other text-related asset. For example: JavaScript, JSON, CSS or XML.

Front End Programming Languages

In web-development, many people often use the terms “front-end” and “client-side” to express the same thing. Specifically, they refer to technology that the end user’s computer executes. That is to say, the browser understands these languages and is thus able to interpret the code.

Consequently, this is the exact opposite of a back-end programming language. Specifically, a web server does not understand HTML, CSS or JavaScript. It simply ensures that files that contain these languages can be downloaded . The web server cannot execute HTML, CSS or JavaScript. (There is an exception with regards to JavaScript, which will be discussed shortly.) But, browsers such as Internet Explorer, FireFox and Chrome do understand these languages, and are able to execute them on the front-end. Accordingly, this means that your computer parses HTML, CSS and JavaScript. In the case of JavaScript,  your computer executes that code.

JavaScript is probably the most commonly used front end web development programing language. Technically, it is a scripting language. Unless you explicitly disable JavaScript in your browser, you see and interact with it every day. When you request a web page, the JavaScript is either in the page, or is downloaded in a separate file. JavaScript runs in your browser, and most people only associate it with those annoying pop-up ads. This was true in the past, but today, JavaScript plays an integral part in creating rich user experiences.

Important Note: Although JavaScript has historically been a 100% front end technology, it is now a fully mature back end language as well. Thanks to the brilliant work and vision of Ryan Dahl, JavaScript can now be run server-side by using Node.js.

Helpful Links for Back End and Front End Languages

Front-End / Client-Side Languages & Technologies




Kevin Chisholm – Blog – Posts about: CSS

Back-End / Server-Side Languages



ASP.NET Overview

ASP.NET and Visual Studio for Web


Node.js (Server-Side JavaScript)

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