What is a CSS class selector?

A CSS class selector is designed to apply styles specifically to elements that possess a designated class attribute. This functionality allows for a more targeted styling approach, enabling developers to define styles that can be reused across various elements throughout the HTML document. When a class selector is utilized in a stylesheet, it is prefixed with a period (.), followed by the class name. For example, if you have a class named "highlight", you would write the selector as .highlight in your CSS.

This selective application enhances maintainability and flexibility in web design, as multiple elements can share the same class and thereby inherit the defined styles. As a result, changing the styling for that class in one place will automatically update all elements using that class, streamlining the design process and fostering consistency across the webpage.

The other options describe different functionalities, such as targeting all elements universally, focusing on specific IDs, or selecting elements based on their position in the document structure, which do not relate to the definition of a class selector.