HTML
HTML is great. It defines the structure of webpages and it determines how data is displayed online. What you’re looking at right now is HTML code, read and interpreted by your browser. But this doesn’t make HTML a programming language.
A Markup Language
HTML is a type of markup language. It encapsulates, or “marks up” data within HTML tags, which define the data and describe its purpose on the webpage. The web browser then reads the HTML, which tells it things like which parts are headings, which parts are paragraphs, which parts are links, etc. The HTML describes the data to the browser, and the browser then displays the data accordingly.