The WayBack Machine on the Internet Archive’s website (archive.org) allows researchers to review previous versions of websites. Please consult the following tutorial to see the tool in action: 

Source: Richard Byrne YouTube Channel

For an introduction on what is indexed in the Wayback Machine, which is located at the top of the page on the website archive.org, please review the Questions and Answers on the Help Page of the Internet Archive, available here: https://help.archive.org/#The_Wayback_Machine