Terms to Know

An overview of the key terms you'll need to know.

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Tech jargon

The world of web technology is full of strange terms and an alphabet soup of acronyms and it can be a bit overwhelming. There are some in particular that you will need to be familiar with before getting started.

The list below should get you kicked off. Look at the Resources tab for links to other great places to learn development terminology.

Note: Many of the links point to Skillcrush, which has changed their URL structure a number of times (more than we can easily keep up with). You may need to use their search bar to locate a given term.

The Web


Short for "Uniform Resource Locator", it's the address of the webpage that you're trying to get.

Read more on Wikipedia or W3C.


The part of the URL which specifies the location of the web server who is going to respond to your request. For instance, vikingcodeschool.com.

Read more on Wikipedia or on Skillcrush.

IP Address

The IP Address is the actual definitive address of a computer or server on the web. All requests you send use this address to locate their destination server and your own IP address to determine where to return the response.

Read more on Wikipedia or on Skillcrush.


The DNS, or "Domain Naming System", maps the human-readable domains like vikingcodeschool.com to their actual IP address locations, that way you only have to remember the human-readable version.

Read more on Wikipedia or HowStuffWorks.


HTTP (HyperText Transfer Protocol) is the protocol used across the web for just about all communication between clients and servers. Basically, it makes sure everyone's speaking the same language and following the same procedure to ask for and receive data.

Read more on W3C.


For secure transactions, the protocol gets a bit more complicated.

Read more on Skillcrush or Wikipedia.


When you're sending email, there are several other protocols which rule the land. Email is a whole other infrastructure that you often don't think about but it's got its own interesting challenges and languages.

Read more on Skillcrush.


An API, or "Application Programming Interface", is basically an exposed part of a web application which lets other applications talk to it. When you request a webpage, you're going in the front door to ask for information. APIs are like side doors that the web server has available for other applications to make their own requests.

Read more on Skillcrush.

Web Server

The web server is the part of your web application which actively receives and responds to incoming HTTP requests from browsers or other applications. There are all kinds of different languages they run on, but they all do basically the same thing.

Read more on HowStuffWorks.


A glitch in the matrix. Also the reason your code won't run, probably because you forgot to end your Ruby block or added an extra semi-colon somewhere. Shame on you.

Read more on Skillcrush.

The Cloud

Instead of running a physical server at the desk next to us, we let Google and others manage giant farms of servers and then we buy virtual space on them to run our applications. It seems like we've still got a physical machine, but it's all virtual... in the cloud.

Read more on Skillcrush.


Delicious little snippets of text that the web application can drop into your browser's memory when it sends back the web page. They help the server remember who you are, what you've looked at, and your preferences. Put that way, it does sound a bit stalker-ish...

Read more on Skillcrush.

404 Error

You'll be seeing it a lot. "Resource Not Found". The error your server will return when someone tries to go to a page that doesn't exist. Many tech companies make fun or amusing 404's to ease the pain of rejection.

Read more on Skillcrush and see an example at Github.


"Search Engine Optimization" is making sure your website is very easy for Google and others to crawl so your customers can find their way there.

Read more on Skillcrush.



"What You See Is What You Get". It's an acronym that applies to some text editors or website builders. Basically, it means that however you drag and drop items in the editor, they will show up exactly that way in the "real" world version of the thing you're building. To contrast, when using text editors you don't "see" anything, so they aren't WYSIWYG's. It's pronounced "Wiz-e-Wig".

Read more on Skillcrush.

Responsive Design

Making your website display well regardless of what size screen or type of device it is viewed on. It "responds" to the browser's specifications.

Read more on Skillcrush.

Grid System

Probably helped get us out of the 90's. A way of visually organizing the content on your pages based on a structured grid. There are tons of different styles, but good design almost always uses some form of grid to align elements.

Read more on Skillcrush.


Red-Green-Blue! Another common way that we uniquely identify colors onscreen, with each value a number from 0 to 255 that corresponds to how much of that color the screen should display. For example, rgb(234,112,16).

Read more on Wikipedia


Only a curse to try and decode sometimes, it's short for "Hexadecimal". It's a way of representing numbers on a 16-digit scale from 0-9 and a-f. You'll most often see it when working with colors, which can be expressed as something like #f4e288, where each pair of numbers corresponds to an RGB color.

Read more on Skillcrush or choose colors with The Hex Hub.

Above the Fold

A newspaper term which means everything you see on the top half of the page (literally "above the fold"). On the web, applies to everything the user sees without having to scroll down. Better put the good stuff up top or you'll lose them!


"Graphical User Interface" is a generic term for a visual interface (like a typical webpage or an application on your computer where you can use the mouse) where the user can interact with it. The typical alternative is the command line, which is a text-based interface.

Read more on Wikipedia.

Developer Tools and Code

Front End / Back End

The user lives on the front end with her browser, the server serves data from the back end. Wait, didn't we cover this too before?

Read more on Skillcrush.


The markup language which specifies the structure of all the pieces of a webpage.

Read more on Skillcrush.


"Cascading Style Sheets" find HTML tags and tell the browser how to display them. That doesn't mean it's okay to use blinking lights or neon backgrounds.

Read more on Skillcrush or from the Web Design Group.


The scripting language used by all browsers. It's not pretty, but it's absolutely everywhere and it's the way you'll get web pages to do anything dynamic. These days, it's kind of taking over the world as more of the intensive computation moves into the browser instead of living on the server.

Read more on Skillcrush


"Asynchronous JavaScript And XML"... basically a way of transferring data between the server and web page which doesn't require the user to refresh the page. It's done wonders for your Facebook feed.

Read more on Skillcrush.


Halfway between writing out your logic in English sentences and expressing it in code. Pseudo-code is a generic term and it's been helping engineers solve complex problems since The Epoch.

Read more on Skillcrush.


One of the most ubiquitous programming languages. It's quite low level and very fast. Just about all other common languages are actually written in C, which is just a few steps above Machine Code.

Read more on Wikipedia


Happiness. A high level language which is written in C but abstracts away all the annoying bits so you can focus on making usable code instead of getting bogged down in verbose syntax and memory management. Almost English-like. Created in Japan.

Read more on Skillcrush.

Ruby Gems

Gems are helpful libraries of Ruby code that you can easily download and plug into your applications. They are part of what makes the Ruby ecosystem so awesome -- lots of developers have made useful code into gems so it's super easy for you to include in your projects.


A generic term for a bunch of code or markup which makes your life easier by writing all the commonly used things for you. That saves you time and gives you a specific structure within which to operate.

Ruby on Rails

The killer web framework written in Ruby. It's just about the fastest way to build web applications. Very opinionated about how you should organize things, and you'll learn to appreciate that.

Read more on Skillcrush.

Command Line

The interactive shell where you can enter commands that will be run by your operating system. Also useful for navigating your file system. Seems intimidating at first, but really just a misunderstood creature. Wait, we just did a whole lesson on this stuff, remember?

Read more on Skillcrush.

Version Control

Very important and something non-developers have probably never heard of. It's like "save" for your code combined with a time machine so you can go back and see exactly who saved what changes when. Incredibly valuable for collaboration as well. Never lose code again!

Read more on Skillcrush.


Git is the most widely used language for version control. The biggest cloud-based repository of these files is Github.

See What is Git for more info.

Open Source

Exposing your code to the world so they can use it and help make it better. Specifically, you allow other people to do whatever they want with it (including make money). "Open Source Software" (OSS) is kind of a big deal in the developer community. Ruby on Rails, for instance, is open source and you couldn't use it otherwise.

Read more on Skillcrush.


CMS is an acronym that actually gets used for all kinds of things, but in this case we're referring to "Content Management Systems". That's just a fancy way of saying "An application that takes care of all a website's content for it". Wordpress is a common example. It generally provides an interface which allows you to update the content of the site (e.g. writing a blog post) without having to literally go in and write a bunch of code each time to display it.

Read more on Skillcrush.


The cornerstone of every web application. This is where everything your users do is saved. Like a giant collection of giant spreadsheets that moves really fast.

Read more on Skillcrush.


The "Structured Query Language" that we use to talk to our databases. A very simple syntax lets you do all kinds of fascinating things.

Read more on SQLcourse.com


"Extensible Markup Language". A markup language that uses tags to specify the structure of the data. HTML is a subset of XML, which can be used to define other languages. XML is used in all kinds of different applications to send data and specify how that data is structured. Otherwise there'd be data anarchy and the machines will have won.

Read more on Wikipedia or W3Schools.


An XML document that describes the structure of other XML documents. Also refers to the description of the structure of your database.


A generic term for high level code that is translated into machine-runnable instructions using an interpreter program as it is run. Most of the languages you'll work with these days are scripting languages (e.g. Ruby and JavaScript). For instance, Ruby code uses the Ruby interpreter program to convert into something the computer can execute as it is being run. This contrasts to a compiled language, which you need to compile ahead of time.

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