How an HTML website is built with three languages.

Programming, or coding, is like solving a puzzle. In a human language like French or Arabic, the puzzle might be the translate a sentence perfectly. In programming, the puzzle could be to make a web page look a certain way, or to make an object on the page move.
So, when a web designer is given an end goal like “create a web page that has this header, this font, these colors, these pictures, and an animated unicorn walking across the screen when users click on this button,” the web designer’s job is to take that big idea and break it apart into tiny pieces, and then translate these pieces into instructions that the computer can understand — including putting all these instructions in the correct order or syntax.

Every page on the web that you visit is built using a sequence of separate instructions, one after another. Your browser (Chrome, Firefox, Safari, and so on) is a big factor in translating code into something we can see on our screens and even interact with. It can be easy to forget that code without a browser is just a text file — it’s when you put that text file into a browser that the magic happens. When you open a web page, your browser fetches the HTML and other programming languages involved and interprets it.
HTML and CSS are actually not technically programming languages; they’re just page structure and style information. But before moving on to JavaScript and other true languages, you need to know the basics of HTML and CSS, as they are on the front end of every web page and application.

In the very early 1990s, HTML was the only language available on the web. Web developers had to painstakingly code static sites, page by page. A lot’s changed since then: Now there are many computer programming languages available. In this post, I’ll talk about HTML, CSS, and one of the most common programming languages: JavaScript.

The Three basic structure Languages

An overview:
• HTML provides the basic structure of sites, which is enhanced and modified by other technologies like CSS and JavaScript.
• CSS is used to control presentation, formatting, and layout.
• JavaScript is used to control the behavior of different elements.
Now, let’s go over each one individually to help you understand the roles each plays on a website and then we’ll cover how they fit together. Let’s start with good old HTML.

HTML

HTML is at the core of every web page, regardless the complexity of a site or number of technologies involved. It’s an essential skill for any web professional. It’s the starting point for anyone learning how to create content for the web. And, luckily for us, it’s surprisingly easy to learn.
HTML stands for HyperText Markup Language. The “markup language” part means that, rather than being a programming language that uses a programming language to perform functions, it uses tags to identify content.
Let me show you what I mean. Take a look at the article below. If I were to ask you to label the types of content on the page, you’d probably do pretty well: There’s the header at the top, then a subheader below it, the body text, and some images at the bottom followed by a few more bits of text.

 

Markup languages work in the same way as you just did when you labeled those content types, except they use code to do it — specifically, they use HTML tags, also known as “elements.” These tags have pretty intuitive names: Header tags, paragraph tags, image tags, and so on.

Every web page is made up of a bunch of these HTML tags denoting each type of content on the page. Each type of content on the page is “wrapped” in, i.e. surrounded by, HTML tags.

For example, the words you’re reading right now are part of a paragraph. If I were coding this web page from scratch (instead of using the WYSIWYG editor), I would have started this paragraph with an opening paragraph tag: <p>. The “tag” part is denoted by open brackets, and the letter “p” tells the computer that we’re opening a paragraph instead of some other type of content.

Once a tag has been opened, all of the content that follows is assumed to be part of that tag until you “close” the tag. When the paragraph ends, I’d put a closing paragraph tag: </p>. Notice that closing tags look exactly the same as opening tags, except there is a forward slash after the left angle bracket. Here’s an example:

<p>This is a paragraph.</p>

Using HTML, you can add headings, format paragraphs, control line breaks, make lists, emphasize text, create special characters, insert images, create links, build tables, control some styling, and much more.

CSS

Whereas HTML was the basic structure of your website, CSS is what gives your entire website its style. Those slick colors, interesting fonts, and background images? All thanks to CSS. It affects the entire mood and tone of a web page, making it an incredibly powerful tool — and an important skill for web developers to learn. It’s also what allows websites to adapt to different screen sizes and device types.

To show you what CSS does to a website, look at the following screenshots. The left screenshot is one with HTML and CSS, and the right screenshot is that same blog post with HTML only.

 

   LEFT: HTML and CSS                             RIGHT: HTML ONLY

Isn’t that prettier?

Put simply, CSS is a list of rules that can assign different properties to HTML tags, either specified to single tags, multiple tags, an entire document, or multiple documents. It exists because, as design elements like fonts and colors were developed, web designers had a lot of trouble adapting HTML to these new features.

You see, HTML, developed back in 1990, was not really intended to show any physical formatting information. It was originally meant only to define a document’s structural content, like headers versus paragraphs. HTML outgrew these new design features, and CSS was invented and released in 1996: All formatting could be removed from HTML documents and stored in separate CSS (.css) files.

So, what exactly does CSS stand for? It stands for Cascading Style Sheets — and “style sheet” refers to the document itself. Ever web browser has a default style sheet, so every web page out there is affected by at least one style sheet — the default style sheet of whatever browser the web page visitor is using — regardless whether or not the web designer applies any styles. For example, my browser’s default font style is Source Sans Pro Light, size 14, so if I visited a web page where the designer didn’t apply a style sheet of their own, I would see the web page in Source Sans Pro Light, size 14.

Obviously, the vast majority of web pages I visit don’t use Source Sans Pro Light, size 14 — that’s because the web designers behind those pages started out with a default style sheet that had a default font style, and then they overrode my browser’s defaults with custom CSS. That’s where the word “cascading” comes into play. Think about a waterfall — as water cascades down the fall, it hits all the rocks on the way down, but only the rocks at the bottom affect where it will end up flowing. In the same way, the last defined style sheet informs my browser which instructions have precedence.

JavaScript

JavaScript is a more complicated language than HTML or CSS, and it wasn’t released in beta form until 1995. Nowadays, JavaScript is supported by all modern web browsers and is used on almost every site on the web for more powerful and complex functionality.

In short, JavaScript is a programming language that lets web developers design interactive sites. Most of the dynamic behavior you’ll see on a web page is thanks to JavaScript, which augments a browser’s default controls and behaviors.

One example of JavaScript in action is boxes that pop up on your screen. Think about the last time you entered your information into an online form and a confirm box popped up, asking you to press “OK” or “Cancel” to proceed. That was made possible because of JavaScript — in the code, you’d find an “if … else …” statement that tells the computer to do one thing if the user clicks “OK,” and a different thing if the user clicks “Cancel.”

Other uses for JavaScript include security password creation, check forms, interactive games, and special effects. It’s also used to build mobile apps and create server-based applications. You can add JavaScript to an HTML document by adding these “scripts,” or snippets of JavaScript code, into your document’s header or body.

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