What's the Difference Between CSS `id` and `class` Selectors?

Understanding the Differences Between id and class in CSS

As a beginner in CSS, differentiating between id and class can be confusing. Both can apply styles to HTML elements, but they have distinct purposes.

Class

A class is used to apply a set of styles to multiple elements consistently throughout a webpage. It allows you to group elements that share similar characteristics, such as a class named "comment" for all comment sections or "button" for all action buttons. Importantly, an element can have multiple classes applied simultaneously, enabling you to define complex styles.

Id

An id, on the other hand, is used to identify a single, unique element on a page. Each id must be unique, and an element can only have one id assigned. This makes id ideal for styling elements that are only present once, such as "main" for a main content container or "header" for the webpage header.

When to Use Each

Use a class when:

• You want to apply similar styles to multiple elements consistently.
• You want an element to belong to multiple groups or have multiple styles applied to it.
• You want to dynamically add or remove styles using JavaScript.

Use an id when:

• You want to style a single, unique element on the page.
• You need to address a specific element directly using CSS or JavaScript.
• You want to create a link to a specific element on the page using anchors.

Example

In the provided code examples:

• Using #main with an id would be appropriate if your webpage only contains one main content area.
• Using .main with a class would be better suited if you plan to have multiple sections with similar styling, such as a sidebar or footer, within the same webpage.

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