How many heading a page should have?

Hi Friends,
For a long time it was considered one of the cardinal rules of HTML and SEO that each individual page of a site should have one <h1> level heading, and one only. Additionally, the rule prescribed that this singular <h1> heading should denote the primary subject matter of the page.

This rule was generally followed with the goal of helping search engines better understand the primary subject matter of each page, so they could determine their relevance to various search phrases, improve search engine accuracy and hence improve rankings for well-crafted sites.