HTML (Hypertext Markup Language) is the standard language used for creating web pages and web applications. It provides the structure of a webpage by defining the various elements, such as headings, paragraphs, images, links, and forms. HTML elements are represented by tags, typically consisting of an opening and closing tag, such as `<p>` for a paragraph or `<a>` for a hyperlink. Attributes are used within tags to provide additional information, like the `href` attribute for specifying the destination of a link.