What is CSS?

What is CSS

When you look at a website, have you ever wondered how it gets its style? Why some text is bigger than other text, or why backgrounds have different colors? This all comes down to CSS. But what exactly is CSS?

Let’s find out!

What is CSS?

CSS stands for Cascading Style Sheets. It’s a language used in web development to style the appearance of content on web pages. When you visit a website, CSS determines how the text, colors, and layouts appear. For example, if you see a web page with a pink background and yellow text, that’s CSS in action.It works alongside HTML. While HTML forms the basic structure of the web page, like building the walls and floors of a house, CSS adds designing elements (say the paint, curtains, and carpets)—it makes the page appealing. Additionally, CSS helps ensure that the web page looks good on all devices, whether it’s a computer, phone, or tablet. 

Advantages of CSS

  • Saves Time: Once you set up CSS, you can use the same style sheet for multiple pages. This means you don’t have to style each page individually, saving a lot of time.
  • Faster Page Loading: Because CSS stylesheets are typically stored separately from the HTML files, browsers can load the CSS file once and cache it. This speeds up the loading of web pages because the browser doesn’t need to reload the CSS every time.
  • Easy Maintenance: With CSS, making a change to the look of a website can be as simple as altering a few lines in a single file. This can drastically cut down the effort needed to maintain and update a website.
  • Consistency Across Pages: CSS ensures that all pages of a website can follow the same styling rules easily. This means your website looks uniform, which is good for branding and user experience.
  • Advanced Styling Capabilities: CSS allows more precise control over the layout and appearance of web elements than HTML does. You can adjust the spacing, alignment, size, and even create animation effects.
  • Responsive Design: CSS makes it easier to create responsive websites that work well on both desktops and mobile devices without needing separate versions.

Prerequisites of CSS

To start learning CSS (Cascading Style Sheets), you don’t need many formal prerequisites. Here are some key points you should know as a beginner:

  • HTML Basics: CSS is used to style web pages that are built with HTML. It’s important to understand HTML because CSS works by selecting HTML elements and applying styles to them. You should know how to create and use HTML tags like <div>, <p>, <h1>, and others.
  • Basic Computer Skills: You should be comfortable with using a computer, managing files, and understanding directories. Since you’ll be writing code and saving it in files, knowing how to create, save, and organize your files on a computer is necessary.
  • Text Editor: To write CSS, you’ll need a text editor. Simple editors like Notepad are okay, but there are better options like Visual Studio Code, Sublime Text, or Atom that can help you by highlighting your code and suggesting corrections.
  • Web Browser: You need a web browser to see how your CSS affects a web page. Browsers like Chrome, Firefox, or Safari let you view your HTML and CSS in action.
  • A Code Editor: Although not a prerequisite for learning the languages themselves, having a code editor will make coding much easier. These tools provide features like syntax highlighting and auto-completion that can help you write code more efficiently.
  • Understanding of Colors and Layout:  A basic sense of design, like how colors work together and the basics of creating a layout, will be very helpful. CSS will ask you to set colors and arrange elements on the screen.
  • Patience and Problem-solving:  Learning CSS can be fun, but sometimes it gets tricky. Being patient and ready to solve problems as they come will make the process smoother.

Components of CSS

Here are the main components of CSS that you should know:

  • Selectors: These are the names you give to pieces of your HTML you want to style. For example, if you want to style all paragraphs, you would use the p selector. If you have a specific item you want to style, like a section with an ID of header, you would use #header.
  • Properties: Once you’ve selected an element, you need to specify what you’re going to change about it. Properties are specific aspects of the element’s style you want to alter. For example, color, font-size, and margin are all properties that control different aspects of how an element appears.
  • Values: These are the settings you apply to a property. For example, if the property is color, a value might be red or #FF0000. If the property is font-size, the value might be 14px or 1em.
  • Declarations: This is a single rule that pairs a property with a value. For example, color: red; is a declaration that sets the color property to red.
  • Declaration Blocks: Multiple declarations can be grouped together in a declaration block, which is wrapped in curly braces {}. For instance, you might have a block that sets several properties for a header, like this:

header {

 color: red;

 font-size: 20px;

 margin: 10px;


  • Rulesets: A ruleset consists of one or more selectors followed by a declaration block. For example:

p {

 color: blue;

 font-size: 18px;


This ruleset changes the color and font size of all paragraphs.

  • Comments: These are non-coding lines that help you keep track of what your CSS is doing and why. In CSS, comments are written inside /* */ markers.

Why Use CSS?

When creating a website, HTML is used to lay out the basic structure, but it doesn’t provide any styling such as colors, fonts, or spacing. That’s where CSS comes in. It lets you style your webpage in many visually appealing ways without altering the underlying structure.

Here are a few key reasons to use CSS:

  • CSS allows you to set styles that can be applied across multiple pages of a website. For example, you can define the font color and background color in one CSS file and have those styles apply to every page. This keeps the look of the site uniform and professional.
  • Instead of writing the same styling rules in every HTML page, you can write them once in a CSS file and link it to all HTML pages. This makes loading pages faster and reduces the amount of code, which can make websites run more smoothly.
  • CSS makes it easy to make changes to your site’s design. If you want to change the color theme or the layout, you can just change a few lines in the CSS file rather than modifying every single page.
  • It offers features like Flexbox and Grid which help you create complex and responsive layouts that adjust to different screen sizes. This is crucial for making websites look good on both computers and mobile devices.

Example of CSS

Here’s a basic example of CSS:

body {

  background-color: lightblue;


h1 {

  color: navy;

  text-align: center;


p {

  font-family: ‘Arial’;

  font-size: 20px;


This CSS example demonstrates how to style different HTML elements on a webpage using basic CSS properties.

Types of CSS

CSS (Cascading Style Sheets) mainly comes in three types:

  • Inline CSS: This type of CSS is used directly within an HTML tag using the “style” attribute. It applies styles only to that specific element. For example, <p style=”color: blue;”>This text is blue.</p> makes just this paragraph blue.
  • Internal CSS: Also known as embedded CSS, this is placed inside the <style> tag within the <head> section of an HTML document. It affects only the styles of elements on that specific webpage. It’s useful for single-page style changes.
  • External CSS: This is the most common and efficient type when working on big projects or multiple pages that share the same styling. Styles are written in a separate file with a .css extension and linked to HTML documents using the <link> tag. This method keeps HTML and CSS code separate, which makes the website easier to manage and update.

How Does CSS Work?

CSS works by selecting elements in the HTML document and applying styles to them. These styles dictate how the content should look and be formatted. Here’s a simple breakdown:

  • Selector: This is the part of CSS that identifies which HTML element or elements the styles will apply to. For example, p targets all <p> tags.
  • Declaration: This is the style rule you apply to the selected elements. A declaration consists of a property and a value, separated by a colon and enclosed in curly braces. For example, p { color: red; } applies a red color to all paragraph texts.
  • Applying Styles: When a webpage loads, the browser reads the HTML code to create a document structure, then it uses CSS to apply styles to this structure. CSS rules can be applied from various sources like external stylesheets, internal stylesheets, or inline styles.
  • Cascading: This term in CSS refers to the priority scheme used to determine which style rules apply if more than one rule matches a specific element. These rules are sorted by importance (e.g., inline styles take precedence over external styles), specificity (more specific selectors override more general ones), and source order (later rules override earlier ones).


By now, you should have a basic understanding of what CSS is and why it’s used so widely in web development. CSS is essential because it helps developers create visually appealing websites that are easy to use on all devices from desktops to smartphones. It gives them the ability to control layout and presentation on a wide range of devices. With CSS, the possibilities for designing a unique and functional website are almost endless.


What is CSS?

  • CSS stands for Cascading Style Sheets.
  • It’s a language used in web development to style the appearance of content on web pages.
  • CSS determines how text, colors, and layouts appear on websites.
  • It works alongside HTML to enhance the visual presentation of web pages.

What is CSS used for?

  • CSS is used to style the appearance of web pages, including text, colors, and layouts.
  • It complements HTML by adding design elements to create visually appealing websites.
  • CSS ensures consistency across different devices, making web pages look good on computers, phones, and tablets.
  • It helps in creating responsive designs that adapt to various screen sizes.

How does CSS work?

  • CSS works by selecting HTML elements and applying styles to them.
  • Styles dictate how content should look and be formatted on web pages.
  • CSS rules can be applied from various sources like external stylesheets, internal stylesheets, or inline styles.
  • Cascading, specificity, and source order determine which style rules apply if multiple rules match a specific element.

What are the types of CSS?

  • Inline CSS: Styles are applied directly within HTML tags using the “style” attribute.
  • Internal CSS: Styles are placed inside the <style> tag within the <head> section of an HTML document.
  • External CSS: Styles are written in a separate file with a .css extension and linked to HTML documents using the <link> tag.

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