An HTML index page is the main or default web page of a website. It usually has the filename index.html or index.htm, and it is located in the root directory of the web server³.

An HTML index page typically contains the basic structure and content of a website, such as the document type declaration, the html element, the head element, and the body element¹.

The document type declaration tells the browser that the document is an HTML5 document. It must be the first thing in the HTML document¹.

The html element is the root element of the HTML document. It usually has a lang attribute to specify the language of the text content on the website².

The head element contains metadata about the HTML document, such as the title, character encoding, viewport, stylesheet links, favicon, etc².

The body element contains the visible content of the HTML document, such as headings, paragraphs, images, links, forms, etc¹.

Here is an example of a basic HTML index page: