Minecraft wiki entry for Advancement, associated text: Advancement icons display a header name and description when hovered over. The advancement descriptions have a unique color depending on the type of advancement with normal and goal advancements having green descriptions and challenge advancements having purple ones. As more advancements are unlocked, new ones become visible, with up to two advancements being displayed ahead of an unlocked one. Unlocked advancements show all of its direct parents advancements (the advancements between the root advancement of the tab and it), even those that have not been unlocked (but only show 2 advancements downstream of advancements already unlocked). Four (Six‌[upcoming: JE 1.19]) advancements, "How Did We Get Here?", "Voluntary Exile", "Hero of the Village", "Arbalistic", "You've Got a Friend in Me"‌[upcoming: JE 1.19], and "Birthday Song"‌[upcoming: JE 1.19] are hidden advancements, meaning that they cannot be viewed by the player until they have been unlocked, regardless if any one of its child advancements (any advancement after it, including all branches) have been unlocked, which would normally display its parent advancements (as advancements can be unlocked and completed in any order).