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Class Vs ID

Last Updated on October 11, 2023 by Abhishek Sharma

CSS is a powerful and used language for designing and styling webpages. With the help of CSS, the developers can change the appearance, layout, and design of the web page. The developer can change the element by using either class or id we will discuss both of them while moving further in this blog, we will also discuss examples of both. We will see the popper use cases of CSS class and css id as it will be helpful for you. Both these are used to target a particular HTML element so that we can style it accordingly.

What are CSS Classes Selectors?

In CSS class is a way to define a group or category of elements that share similar styles. It is denoted by a period (.) followed by a name, and it can be applied to any HTML element using the "class" attribute.

The main purpose of classes in CSS is to group and apply styles to multiple elements with similar characteristics. Classes provide a way to define a set of styles that can be reused across different elements or sections of a website, promoting consistency in design. For example, you can define a class for buttons, headings, or navigation menus, and apply the same class to all relevant elements to achieve consistent styling throughout the website.

Syntax for Defining Classes

The user needs to follow the syntax mentioned below to define and use classes in css

.class-name {
/* Styles go here */

The period (.) followed by the class name is used to define the class selector, which targets all elements with that specific class. Inside the curly braces, you can specify the styles that you want to apply to the elements of the class. These styles can include properties such as color, font size, margin, padding, and more, allowing you to customize the appearance of elements with the class according to your design requirements.

Example of CSS Class
Now we will discuss the example of a class with proper code and output.


This is a box with some text

CSS Code

.box {
background-color: #f0f0f0;
padding: 10px;
border: 1px solid #ccc;
width: 200px;
margin: 0 auto;
.box-text {
color: #333;
font-size: 16px;
text-align: center;

Explanation of the Above Example
In this example, we have an HTML div element with a class of "box". We then define a set of styles in the CSS for elements with the class "box", such as the background color, padding, border, width, and margin.
Inside the "box" div, we have a paragraph element with a class of "box-text". We then define another set of styles in the CSS for elements with the class "box-text", such as the color, font-size, and text-align.
In CSS, an ID is a unique identifier that is used to target and style a specific element on a web page. IDs are defined using the "id" attribute in HTML and are prefixed with a "#" symbol in CSS.
IDs are meant to be unique within a web page, which means that each element should have a unique ID assigned to it. Unlike classes, which can be applied to multiple elements, IDs should only be used to target and style a single element.

Syntax of ID in CSS

id-name {

/* Styles go here */

You have to use the “#” operator folwed by the id name after that you can use the id to write the styles on the corresponding element that you want to implement on it.
Example of ID in CSS
In this section, we will discuss the example of using id in css with code, output, and explanation. In the following example, we will style a header and a navigation menu using id in css.



Welcome to my website

CSS Code

mainHeader {

  background-color: #000;
  color: #fff;
  padding: 20px;
#mainNav {
  background-color: #333;
  padding: 10px;

#mainNav ul {
  list-style-type: none;
  margin: 0;
  padding: 0;

#mainNav li {
  display: inline;
  margin-right: 10px;

#mainNav a {
  color: #fff;
  text-decoration: none;

Explanation of the Above Example
In this example, we have defined an ID "mainHeader" for a header element and applied styles to it using CSS. The ID allows us to uniquely style the header element with a specific background color, text color, and padding. We have used an ID "mainNav" to style a navigation menu. The ID allows us to apply styles to the navigation menu, its list items, and links, providing a unique appearance for the menu.

Differences between Class and ID

Although classes and IDs will seem so much similar to you there are many differences among them and we will discuss some of them in this blog section.

Property Class ID
Usage Classes can be applied to multiple elements on a web page. IDs are meant to uniquely identify a single element on a page
Flexibility Classes provide more flexibility in terms of styling as they can be easily modified in the CSS file IDs are less flexible as changing the styles of an element with an ID requires modifying the ID definition in the CSS file.
Reusability Classes are more reusable compared to IDs IDs are less compared to classes
Priority Classes have a lower priority compared to IDs IDs have a higher priority compared to Classes
Semantics Classes are generally used to define styles based on the characteristics or purpose of elements IDs are typically used for uniquely identifying elements

Best practices for using classes and Ids in CSS:

In this section, we will discuss some of the best practices for using class and Id in css.

  • You should use classes for styling groups of elements that share similar properties or characteristics.
  • The IDs should be used for unique elements that have different purposes or characteristics.
  • You should avoid IDs for styling purposes it is advised to use classes for styling.
  • IDs are more specific and when they are present along with the class of the same element then the styles that are specified by the ID will be effective or implemented.
  • It is advised to give the name o the classes and IDs as more related to the element or work they are representing so that the code is more schematic.

By summarising classes and IDs are both important tools in CSS for applying styles to web elements, but they have some key differences in how they function and when they should be used. Classes are more versatile and reusable, while IDs are more specific and intended for unique elements. By following best practices and understanding the differences between classes and IDs, web developers can effectively use them to create consistent, maintainable, and semantic CSS code for their web projects.

FAQs related to CSS class

1. How do I create a CSS class selector?
To create a CSS class selector, you simply prefix the class name with a period (dot). For example, to create a class selector for a class named "my-class," you would write .my-class { / styles here / } in your CSS file.

2. How do I apply a CSS class to an HTML element?
To apply a CSS class to an HTML element, you add the class attribute to the element and set it equal to the name of the class you want to apply. For example,


3. Can I use the same class on multiple elements?
Yes, you can use the same class on multiple HTML elements. This is one of the key benefits of CSS class selectors; they allow you to apply the same styles to multiple elements.

4. How do I select elements with a specific class using CSS?
To select elements with a specific class using CSS, you use the class selector followed by the class name. For example, .my-class { / styles here / } would select all elements with the class "my-class."

5. Can an HTML element have multiple classes?
Yes, HTML elements can have multiple classes by separating them with spaces in the class attribute. For example,

. This allows you to apply styles from multiple CSS class selectors to the same element.

6. What happens if two classes have conflicting styles?
If two classes applied to the same element have conflicting styles, the styles of the class that is defined later in your CSS file or has higher specificity will take precedence.

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