How to define a tag in html?

Question

Some tags like <a hfer> or hyperlink was defined many years ago . It was defined by someone. So my question is how to make or define a new tag(like python def function) in html ?

Answer 1

You can just write your own custom tag i.e. <tony> ... </tony>. But there's more to it, you need to setup the rules for its appearance using CSS, otherwise it'll look just like a regular text.