What is the primary function of a CSS selector?

The primary function of a CSS selector is to select elements in the HTML document to apply styles. CSS (Cascading Style Sheets) is a language used to describe the presentation of web pages written in HTML or XML. Within CSS, selectors are the means by which specific elements on a webpage are targeted, allowing developers to apply styling rules such as colors, fonts, spacing, and layout characteristics.

By using selectors, developers can ensure that their styling is applied precisely to the desired elements, whether they are targeting all instances of an element (like all paragraphs), elements with a specific class, or even those matched by complex relationships within the document structure (like child or descendant selectors).

Understanding how to use selectors effectively is fundamental in web development, enabling the separation of content (HTML) from presentation (CSS), which in turn enhances maintainability and flexibility in design.