This is a backslash. It has a bunch of other names too. It's an uncommon bit of punctuation in the day-to-day, but it does get used in some programming languages. And it gets misused often. If you're describing a URL (web address), they often have forward slashes. But they typically don't have backslashes, which is a common point of confusion. It's {year} folks, let's get this one right. To learn more, check this out.