What is CSS?

CSS (CASCADING STYLE SHEETS) is a web coding language that renders a web page a certain way. The key word here is “style,” and that’s what CSS is all about.

CSS doesn’t replace HTML (Hypertext Markup Language) as a web design language, however; it works hand-in-hand with it. While HTML organizes the content of a site, the CSS tells it how to display and behave.

The Anatomy of a Webpage

Think of HTML as the bones of a website. It is the underlying structure and organization. In this analogy, CSS would be the muscles and skin, filling in and building upon that foundation.

How CSS Works

Since we’ve already covered an “S”, it’s time to discuss how CSS works. The other “S” stands for “sheets” as CSS is typically contained in a separate file sheet that gets called by the browser when rendering the page.

Multiple style sheets can even inform a single page, which is where the “C” comes in: Cascading. Broader style sheets handle sweeping functionality whereas more specific ones may only apply in certain circumstances. In this regard, style sheets follow a hierarchy when triggered, giving practical action to the “cascading” description of their name.

Because of these sheets, it’s possible to completely change the look of a site by making a few changes to CSS rather than going through every single HTML tag in the main body of the site and throughout every single page.

Practical Applications

CSS is typically used to control general design concerns such as the type of font combination to consistently use across the site; that way, HTML wouldn’t need to repetitively shape each instance a certain style was needed. When a CSS file is edited, it acts as a “master” list, which means that it will affect all of the attributes across every page simply from the revisions to the one file. Whether your site has five pages or five thousand, this can be a powerful tool!

CSS has a number of different commands to affect color, positioning, size, spacing and layer order, according to W3Schools. Clever designers are even able to take advantage of certain rules put together or having javascript interact with the CSS in order to create dazzling effects such as parallax scrolling.

Unlike HTML, which uses the < and > brackets and forward slashes to designate “tags,” CSS relies on the { and } curly brackets as well as colons and semicolons to define rules that apply to certain classes or families. For example,

h1 {
color: blue;
text-decoration: underline;

states content tagged as < H1 > via HTML will always be rendered in blue and have an underline.

With this type of functionality, CSS can be used to create and format divisions, designed for laying out pages much more easily than setting up tables to put the content in, as well as keeping track of commonly used styles, adding hover applications to links and even wholly tackling a site’s responsive design for mobile functionality.

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A Coding Essential

CSS didn’t start out as a widely used language for the web, but it’s now becoming increasingly rare to find any site without it. Due to its flexibility and overarching capability, designing and building a site is easier, especially when the designer must be conscious about brand adherence, according to Mozilla. CSS is a must-learn for any aspiring web developer.