The Barrier Alice is an extremely useful and coveted ability among Alices. The general ability of the Barrier Alice is to make a shield that can deflect Alices and attacks, but each individual user's Alice differs in strength and extra abilities (e.g. Masachika Shiki's barrier contains some telepathic ability). The Barrier Alice, especially Himemiya's Barrier Alice, has the power to inhibit and weaken other Alices inside it, as was shown during the Hanahime arc when the Dangerous Abilities students were inside the Hanahime den (which had a strong barrier cast on it by Himemiya to weaken Alices).
The barrier created by this Alice can also be of physical use. Shiki, Himemiya, and Shido's Barrier Alices have been seen to prevent bombs and people from following. Shiki's Alice has also been shown capable of removing unwanted persons from the areas protected by his barriers.