HTML codes are the building blocks of web pages, allowing developers to create and structure content on the internet. HTML stands for HyperText Markup Language, and it uses a series of tags to define elements like headings, paragraphs, links, and images. Each tag is enclosed in angle brackets, such as <tagname>, and often comes in pairs with an opening and closing tag. These codes help browsers understand how to display text and multimedia content. For example, the <p> tag is used for paragraphs, while the <a> tag creates hyperlinks. By using HTML codes, developers can design user-friendly and visually appealing websites.