The RegEx tool is kind of like the Swiss Army Knife of parsing in Alteryx; there are a whole lot of ways you can use it to do things faster or more effectively, but even if you just use the blade it's still immensely useful. Sometimes that's all you need, but if you do take the time to figure out how to use a few other tools in that knife, you'll start to see that there isn't much you can't do with it.
