The `<a>` tag, or anchor tag, is an essential HTML element used to create hyperlinks. It allows users to navigate from one webpage to another or to different sections within the same page. The tag typically includes an `href` attribute, which specifies the URL of the destination. In addition to linking to web pages, the `<a>` tag can also link to email addresses using the `mailto:` protocol or to files for download. This versatility makes it a fundamental component of web design, enhancing user experience by providing easy access to related content.