HTML is made up of tags that are used to structure and style text on web pages. There are two types of tags - opening and closing tags. Text and other elements are placed between opening and closing tags to determine how they are displayed. Some common tags include <head> for page properties, <body> for content, and <font> for styling text with options for color, size, and face. Positioning and formatting text is achieved through tags like <center> to align content.