HTML is basically a language on the internet for website. It basically consists of multiple pages where each pages written in .html extension.
Currently the latest version is HTML5 where new elements are added.
It is the abbreviation of Hyper text markup language that means you can embed links inside the text. When click on any link this will take you another page of the website which is also build on .html extension.
Documents are displayed on browser where it reads the document, interprets, format and show on browser.
<html> <head> <title>Page Title</title> </head> <body> Content goes here... </body> </html>