Have you ever been on to a website to find something, but found the page has changed, and what you wanted is no longer there?
Or maybe you are looking into a company and want to prove or disprove something which you know was on their website, but they are denying?
The WayBackMachine at https://archive.org/web/ logs historic web pages and allows you to view snapshots of those pages at given times.
Try it with your website and see what historic data is held about you!