Barrier
minecraft:barrierThe Barrier is an invisible, indestructible solid block used to build boundaries that players and mobs cannot pass. It cannot be obtained in survival and is only available through the /give command or in Creative mode with cheats enabled. While a player holds a barrier item, all placed barriers show up as a red box with a diagonal slash so builders can see them, but they become completely invisible again once the item is put away.
FAQ
How do you get a Barrier block?
Barriers cannot be found or crafted in survival; obtain them with the /give command or from the Creative inventory when cheats are enabled.
Why are Barriers invisible?
Barriers are designed for map makers to build unobtrusive boundaries, so they render fully invisible unless you are holding a barrier item.
How can you see placed Barriers?
Hold a barrier item and every nearby placed barrier appears as a red box with a diagonal slash, making them easy to locate and remove.
How is a Barrier different from bedrock?
Both are unbreakable in survival, but bedrock is a visible textured block while a barrier stays completely invisible, ideal for hidden walls.