Minecraft wiki entry for Advancement_guide, associated text: Jump into an end portal, which is found in end portal rooms in strongholds. You will get the advancement before the actual terrain loads. Once the End's terrain loads, you will get "The End" advancement (the difference is the question mark). Make sure you come prepared before going to the End, because the only way out is to either defeat the ender dragon, or die in the attempt. In hardcore mode, to beat the ender dragon, you must not die otherwise you can't respawn.