Each header-format level has an open and a close tag. The highest-level header-format tag is <H1> and the lowest is <H6>.
The different headers appear in different sizes.
See an example
One thing to remember about HTML is that the actual fonts, sizes, and layout of the final presentation can be altered by users based on the preferences they have set on their browser.
The horizontal rule tag is <HR>. It produces a skinny line
accross the page (useful for seperating information).
See an example