What do you call the first string of characters inside an HTML tag?

Question

This is an element: <p class="blah">Hi World!</p>

This is a tag: <p class="blah">

But what is the proper technical name for the p inside the tag?

Answer 1

It’s the tag name. From 8.1.2.1:

2. The next few characters of a start tag must be the element's tag name.