A H1 tag is a semantic HTML tag used to mark the importance of a heading text on a webpage. The H1 to H6 tags are used to define HTML headings. H1 defines the most important heading and H6 defines the least important one.
The use of H1 tag for a targeted keyword or query is recommended for search engine optimization among many other "on page" elements. For search engines like Google, the use of an H1 tag for a given keyword is a signal that the page is probably focused on the keyword.
For the heading on this page an H1 tag is used as below: