In CSS, Class is used to style the element with the specified class. Classes are often used for group objects that want to have the same format attribute, each class name can be used with multiple elements.

To declare Class in CSS, we use the following syntax:

 .ten_class { 
  định dạng các thuộc tính CSS 
 } 

For example:

 .quantrimang { 
  background-color: black; 
  color: white; 
  font-size: 20px; 

To define HTML elements by class name, we use class="ten_class" .

For example:

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Note :

1. Class can be used with any HTML element.
2. Class names are only allowed to contain letters, numbers, underscores _ , hyphens - . Class name should not start with numbers.
3. The class name distinguishes between uppercase and lowercase letters.

Example 1: Select and style all elements with class = "intro":

 .intro { 
  background-color: #58257b; 
  color: white; 
 } 

Result:

Full code:

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Technology