h1-h6
Definition and Usage
The <h1>,<h2>,<h3>,<h4>,<h5> and <h6> tags are used to define HTML headings. The rank is given in the heading name and<h1> has the highest rank and <h6> has the lowest rank.
Browsers typically render the various headings in different sizes - with <h1> being the largest and <h6>being the smallest.
<h1> defines the most important heading and top-level heading or  <h6> defines the least important heading and  low-level heading.
Syntax
The<h1> tag is written as <h1></h1> with the heading text inserted between the start and end tags.
<h1>Heading</h1>
<h2>Heading</h2>