A proximity blast was a special phaser and laser cannon beam setting that was employed on Federation starships.
The proximity blast function operated by firing phasers in a concentrated bolt of energy, rather than a continuous beam. The phaser blast would then detonate at a predetermined point in space, affecting any ship or object within the blast radius. The proximity blast was mostly used during the Federation-Klingon War by ships such as the USS Discovery and the USS Shenzhou. (DIS: "Battle at the Binary Stars")
The proximity blast setting was used in 2266 by the USS Enterprise while engaging in combat with a Romulan Bird-of-Prey. As the Romulan ship was equipped with an advanced cloaking device, the proximity blast function proved useful against it, as a more precise targeting of the vessel was impossible. (TOS: "Balance of Terror")
The Enterprise used the proximity blast setting again a year later, when engaged in combat with a Klingon D7-class battle cruiser. The Enterprise was successfully able to destroy the Klingon vessel using blasts set to one hundred percent dispersal pattern. (TOS: "Errand of Mercy")
The USS Reliant used a semi beam/proximity blast when cutting into the USS Enterprise's hull and damaging the ship's warp core after being hijacked by Khan Noonien Singh and his followers in 2285. (Star Trek II: The Wrath of Khan)
Ships of the alternate reality such as the USS Kelvin, the USS Enterprise and the USS Vengeance used proximity blasts quite frequently. (Star Trek; Star Trek Into Darkness; Star Trek Beyond)