The Guest was a feature created for the intended use of letting newcomers test Roblox before making an official account. They were introduced on September 26, 2008
Guests were a feature on Roblox that date back to September 28th, 2008 where a new feature was created where players who want to experience Roblox without making an account on there. During AlbertsStuff, he mainly made fun of Guests for being unexperienced at Roblox. He even once met a sub-species of Guests called Prestons when he was dating somebody with a mansion.
Removal of Guests
On October 3, 2017, Guests were officially removed from Roblox, though you could still get in the game as a guest after the removal for many different reasons until November 24, 2018, when they were fully removed, as when you try to get in a game, it shows an error code. Nightgaladeld stated that the reason was to increase the number of users in Roblox. Unregistered users can still access the website, but cannot play games, change an avatar, leave comments, or create things. Most players liked this idea; however, some players were angry at Roblox and started protesting in places like the Roblox forum to bring them back.
There have been numerous sightings of guests in games even after the removal, mostly from people using third-party tools to join games as guests or using mobile. Users including Softdroid have e-mailed roblox to bring the guest feature back, but so far it looks like guests are yet to be returned. The cookie named GuestData can still be found in ROBLOX's cookies but it seems to have no functionality till this day.