Edward Son

The weird glitchy & hacky text is known as "Zalgo | Glitch | Creepy | Crazy" text font and is probably what most people are using this converter for. The reason it makes glitchy text fonts is that Unicode has a special notation for diacritic marks (those strange little symbols that are above or below characters that you see in French, Spanish, mathematics notations, etc.).

Happily, Unicode allows us to add as many strange marks to each character as we like, and so we can take advantage of that to convert text into weird hacky tet which you can copy and paste to YouTube comments so people know you're an l33t h4ck3r.