Are you a Web Developer? Let me share with you some forbidden knowledge.
<center> centers everything. If you do this ...
<center> <h1> Does this really work? </h1> </center>
..., then it does this ...
You tell me.
.... It can center things inside divs. You can use display:inline-block to have multiple things side by side but centered. It just works how you would expect it to.
Why don't they want you to know this?
This is what I call Forbidden HTML. Many years ago, there was this meme (is there a word for intellectual fad?) called "The Semantic Web." The idea was that HTML should only describe the information on a web page, and CSS should be where all the style goes. This was so that programs and robots could read the internet easier, so people could reuse website's contents in new ways the original author didn't think of. <center> describes style, not content, so they don't want you using it.
I could get behind the idea of "The Semantic Web," but realistically, that idea is dead. No one sees the internet as this great collaborative project, but people see their parts of the web as their own personal fiefdoms. Why would they want to make it easier for someone else to use their stuff in ways they didn't intend? And besides, websites these days use a bunch of weird dynamically loaded stuff, so programs can't easily parse modern websites anyways. I see no harm in using <center>, and I will continue to use it. Ignore everyone telling you it doesn't work. They're lying.