What is a index.html file
A file with the HTM or HTML file extension is a Hypertext Markup Language file and is the standard web page file type on the internet. Since HTM files are text-only files, they just contain text (like what you're reading now), as well as text references to other external files (like the image in this article). The index page is the URL or local file that automatically loads when a web browser starts and when the browser's 'home' button is pressed. The term is also used to refer to the front page, web server directory index, or main web page of a website of a group, company, organization, or individual.