When I was little we had an Amstrad PCW. On it was a word processor called LocoScript. I loved that you could write a document on it, save it and come back to it later to add more, which was a novelty at the time.
But what I most liked about it was that all the files had 8 characters followed by a dot and then 3 characters. Those 3 characters were not the file type, as you'd expect, they actually accepted any letters. So effectively your file names could be 11 characters long, with a dot randomly before the final 3.
But that's not the important part of this article. The important point here is that this is pre-Windows (yes, I'm old). These days if you want to make some of your text bold you just press a button. But with no Windows and no mouse, all you can do is to use the keyboard.
If you wanted to make the next bit of text bold you pressed the + key and then the b key. When you wanted your text to stop being bold you pressed the - key and then the b key.
HTML is pretty similar. If you want your text to be bold then you type
<b> and when you want it to stop being bold then you type
</b>. Okay, so these days you'd actually do that with CSS, but you'd still need some sort of tag around your text, even if it's not b (or strong) But it's the same principle of how you set your text to be bold in LocoScript.
Although there was one point that tripped me up when I first learnt HTML. In LocoScript bold is b, italics is i and underline is ul. In HTML bold is b, italics is i and underline is... u. ul is an unordered list.