What is the purpose of a CSS selector?

The purpose of a CSS selector is to target HTML elements in order to apply specific styles to them. When you write CSS, you use selectors to identify which elements on a webpage should be affected by the rules you define. For instance, you could use a class selector to style all elements that share the same class or an ID selector to style a specific element. This targeting is crucial because it allows web developers to separate how HTML content is structured from how it is visually presented, enabling more organized and maintainable code.

In contrast, adding scripts to a webpage, validating form inputs, or connecting to a database pertain to different aspects of web development. Scripts are generally added using JavaScript, form validation involves checking user input before submission, and database connections usually require server-side programming, which is outside the scope of CSS. As such, these functions do not relate to the role of CSS selectors in styling HTML elements.