Eye of Anubis Hologram
The Eye of Anubis Hologram is a foil symbol placed at the bottom right of all official Yu-Gi-Oh! cards, with the exception of some very early prints in the OCG such as those in Starter Box. Contrary to its appearance, it is not a sticker, being printed directly onto the card.
The hologram serves as counterfeit protection as well as being used to identify the edition of a card. Limited Edition and 1st Edition cards have a gold Eye of Anubis Hologram; Unlimited Edition cards have a silver Eye of Anubis Hologram. Despite not having a listed edition, Ticket Cards have a gold Eye of Anubis Hologram, even when printed in Unlimited Edition sets.
Official Proxy images of cards lack this hologram, either excluding it entirely or replacing it with a solid square.