HTML (Ngôn ngữ đánh dấu siêu văn bản), là một ngôn ngữ mang tính miêu tả chỉ dành riêng cho cấu trúc trang web.
Vào năm 1990, như một phần của công trình thiết kế web {{glossary("World Wide Web","Web")}}, Tim Berners-Lee tạo ra định nghĩa {{glossary("hypertext")}}, thứ mà đã được Berners-Lee chính thức công nhận vào năm tiếp theo thông qua markup được dựa phần lớn vào{{glossary("SGML")}}. The {{glossary("IETF")}} began formally specifying HTML in 1993, and after several drafts released version 2.0 in 1995. In 1994 Berners-Lee founded the {{glossary("W3C")}} to develop the Web. In 1996, the W3C took over the HTML work and published the HTML 3.2 recommendation a year later. HTML 4.0 was released in 1999 and became an {{glossary("ISO")}} standard in 2000.
At that time, the W3C nearly abandoned HTML in favor of {{glossary("XHTML")}}, prompting the founding of an independent group called {{glossary("WHATWG")}} in 2004. Thanks to WHATWG, work on {{glossary("HTML5")}} continued: the two organizations released the first draft in 2008 and the final standard in 2014.
An HTML document is a plaintext document structured with {{glossary("element","elements")}}. Elements are surrounded by matching opening and closing {{Glossary("tag","tags")}}. Each tag begins and ends with angle brackets (<>). There are a few empty or void tags that cannot enclose any text, for instance {{htmlelement("img")}}.
You can extend HTML tags with {{Glossary("attribute","attributes")}}, which provide additional information affecting how the browser interprets the element:
An HTML file is normally saved with an .htm or .html extension, served by a {{Glossary("Server","web server")}}, and can be rendered by any {{Glossary("Browser","Web browser")}}.