What is a class selector in CSS primarily used for?

A class selector in CSS is primarily used to select multiple elements that share the same class name. When you define a class in your CSS, you do so by using a period (.) followed by the class name (for example, .classname). This allows you to apply the same styles to any number of HTML elements that utilize that class, promoting consistency and reducing redundancy in your stylesheet.

For instance, if you create a class called "highlight" and apply it to several elements, any styles defined for that class will automatically apply to all those elements, enabling a uniform look across your webpage. This feature of class selectors greatly enhances the ability to manage and maintain styles across larger web projects.

Other options, while valid in their own contexts, do not encompass the key functionality of class selectors. Selecting an individual HTML element typically involves ID selectors or element selectors; applying styles based on the parent refers more to child or descendant selectors; and selecting elements by type alone pertains to the use of type selectors (like div, p, etc.). The unique strength of class selectors lies in their ability to target multiple elements efficiently.