Title
H1 tags improve user experience because they are part of the structure of the web page
H1 is the most prominent part of the page, then H2, then H3, and so on.
H1 is the big title, which should be the largest title of each web page, and usually the article title will also be set to your Meta title
H2 can be used to separate the topics or subtitles of each paragraph in an article, and you can have many at the same time.
H3 is usually used as a sub-point in each paragraph, or as a sub-heading that you want to emphasize.
H4, H5, and H6 are less depending on the situation, unless you subdivide the article into very fine details.