The main element represents the main content of the body of a document or application. -w3c
The <main> tag in HTML represents the central topic or core content of the document body. It is a semantic and structural element introduced in HTML5.
<body> <!-- Other content such as header, nav --> <main> <!-- main content of the document body --> </main> <!-- Other content such as footer --> </body>
The <main> element is also useful for screen readers to skip the navigation and other irrelevant content and jump directly to the core content of the document.
A document should only contain a single <main> element.