Glassing

Purification is a Protoss war technique used to destroy all life on planetary surfaces.

The Protoss have used the technique four times in recent history, each time to kill Zerg present on the planet.

When the Protoss discovered the extent of the Zerg infestation of Chau Sara, Executor Tassadar reluctantly ordered his ships to power up their weapons, destroying the planet. At least two ships, firing massive energy beams, obliterated most or all life. A small number of Marines, including Andre Madrid, survived the attack. *

Tassadar avoided attacking the next infected world, Mar Sara, until after the Terrans had evacuated. Several hours after the escape, Tassadar's forces again sterilized the planet.

A large war between the Zerg, Terran Confederacy and Sons of Korhal broke out on Antiga Prime. After a particularly devastating Zerg attack on the Confederacy (guided by psi emitters), Tassadar's forces attacked the planet, purifying it.

The most recent example took place under mysterious circumstances on the ice world of Braxis. The planet "refroze" since the incident.
 * Main article: Resurrection IV.