What is the difference between a class and an ID in CSS?

A class in CSS is designed to be reusable across multiple elements, making it suitable for styling groups of elements with similar characteristics. This allows for efficient and consistent design since you can apply the same class to different HTML elements to achieve a uniform look. In contrast, an ID is meant to be unique within an HTML document. Each element can have only one ID, and each ID should only be assigned to one specific element. This uniqueness is useful for applying styles or scripts to a specific element without affecting others.

Understanding this distinction is crucial for web design because it influences how you structure your HTML and CSS for maintainability and clarity. In scenarios where multiple elements share the same styling, classes streamline the process, while IDs allow for precise targeting of individual elements. This helps in creating effective designs and user interfaces on websites.