In Cascading Style Sheets (CSS), classes and IDs are used to define the styling of HTML elements. Both classes and IDs are used to target specific elements in the HTML markup, but they have some key differences.
CSS Classes:
A class is a reusable selector that can be applied to multiple HTML elements. It is defined with a period (.) followed by a name that is unique to the class. For example:
.my-class {
color: blue;
font-size: 16px;
}
In the above example, the class “my-class” is defined, which can be applied to any HTML element that needs to have the same styling. To apply the class to an HTML element, we use the class attribute, like this:
<p class="my-class">This text will be styled with the properties defined in the .my-class CSS rule.</p>
Classes are ideal for when you want to apply a specific style to multiple elements on a page. By using a class, you can avoid repeating the same styles for each element, making your CSS code more efficient and easier to maintain.
CSS IDs:
An ID is a unique selector that is used to identify a single HTML element on a page. It is defined with a hash symbol (#) followed by a unique name. For example:
#my-id {
color: red;
font-size: 20px;
}
In the above example, the ID “my-id” is defined, which can be applied to a single HTML element. To apply the ID to an HTML element, we use the id attribute, like this:
<p id="my-id">This text will be styled with the properties defined in the #my-id CSS rule.</p>
IDs are ideal for when you want to apply a specific style to a single element on a page. However, it is important to note that an ID should only be used once on a page. If you use the same ID for multiple elements, the CSS styling may not work correctly.
Differences:
The key differences between classes and IDs in CSS are:
- Reusability: A class can be used multiple times on a page, whereas an ID can only be used once.
- Specificity: An ID is more specific than a class, which means that the CSS styling defined for an ID will take precedence over the styling defined for a class.
- Naming Convention: Classes are named with a period (.) followed by a unique name, while IDs are named with a hash symbol (#) followed by a unique name.
In summary, both classes and IDs are useful for defining CSS styles for HTML elements, but they are used in different situations. Classes are best for applying a style to multiple elements, while IDs are best for applying a style to a single element. By understanding the differences between classes and IDs, you can make your CSS code more efficient and effective.