HTML (Hypertext Markup Language) is used to create web pages. It uses tags to define headings, paragraphs, lists, links and other elements. Some key HTML tags are <html> <head> <title> <body> <h1>-<h6> <p> <ul> <ol> <li> <a> <img>. HTML pages can be written using a basic text editor and have the .html file extension. The browser interprets the HTML tags to display the structured page content.