What does a selector do in CSS?

A selector in CSS is crucial because it identifies the HTML elements that the subsequent style rules will apply to. When writing CSS, you use selectors to target specific elements on a webpage, allowing you to control their appearance through styling properties such as color, font, size, margins, and more. This is fundamental in web design as it enables you to create visually attractive and well-structured content by applying styles consistently across various HTML components.

For example, if you have a class selector for paragraphs (e.g., .my-paragraph), any HTML paragraph element with that class will have the styles defined under it applied, affecting its visual rendering on the page. This functionality is essential for maintaining design coherence and enhancing user experience on the web.