From Halopedia, the Halo wiki
Halo Waypoint has been updated numerous times since its inception in September 2009 when the site was first created. Sometimes these updates are treated like a refresh of the site and all content is removed in favor of starting anew. Halopedia records each "refresh" as a new "Era" in order to keep information organised.
How to archive
As this is a very varied process in archiving stuff there is no easy way for us to explain how to archive things. For tips however follow this link here.
2009 to 2014
These archives are based on Halo Waypoints site between its inception on September 2009, and October 13, 2014.
2014 to 2020
These archives are based on Halo Waypoints site between October 13, 2014 and the website update in 2020.
2020 to present
These archives are based on Halo Waypoints site between 2020 and the current time.
These archives are a very selective list of notable "Forum threads" that are recorded for one reason or another.