Border

Border blocks are unbreakable blocks that prohibit movement through, over or under them. They are exclusive to and.

Obtaining
Border blocks can be obtained only by using commands, or using in creative mode. No tool or explosion can damage them (they act as if they have no collision box when you try).

Usage
Border blocks are generally used to surround an area to prevent students (or players) and mobs from entering it, or to confine them within the surrounded area. They create an invisible, impassable barrier of infinite height above and below themselves (but not sideways). They prevent players who lack the worldbuilder ability from doing any of the following: Most mobs cannot pass over or under border blocks and cannot target a player or other mob through them. However, they do not stop the Ender Dragon, and weapons, projectiles, and explosions interact with them as if they were regular walls. Because of this, it is possible to use an ender pearl.
 * Jumping, climbing, tunneling, or swimming over or under them,
 * Walking through them,
 * Building (placing or destroying blocks) over or under them,
 * Destroying the border block.

Placing or breaking a border block requires the worldbuilder or operator ability, which can be granted to the player by an operator or host. Border blocks continuously emit red particles.

When used $$ without Education Edition features enabled, border blocks are indestructible, with a height of 1.5 blocks and a width of 1 block.

Piston interactivity
Border cannot be pushed by pistons. It also cannot be pushed nor pulled by sticky pistons.

Trivia

 * Border blocks and walls share the same block models and inventory model.