Using h1 tags

I did a test which is below: I put the h1 before and after one sentence in html thinking that only that sentence would be affected, but the entire post was affected.
I just discovered that I need to insert a list item tag into each line of text to keep them from being affected by the h1 h2 etc tags.
Is there a syntax for affecting one word or sentence without affecting all subsequent text?

<h1>Below is a list of the specialty workshops TTT will offer this year.<h1>