By default, browsers do not recognize all the characters you may enter into your code. For instance, a < or a > sign is normally not printed to the screen, because the browser interprets it as a tag. So what do you do if you need to use one of these characters? Simple: Use an HTML character entity. This is a special code that you use in place of whatever symbol you want to use that browsers render as that symbol.
Now, before you run off to memorize all the available HTML entities (and there are a lot), check this out: HTML Editor can generate them for you. Just click the Characters tab on the left-hand side of the screen, position your cursor in the location on the page where you want the character to appear, and then double-click the character of your choice. You can also drag the character to the desired location on the page. The code will automatically be inserted for you.