The cutting beam was a starship weapon created by the Borg Collective and was used by their vessels in combat against enemy ships.
This Borg weapon fires a beam weapon which was designed to penetrate a target vessels shields and hull in order to cut pieces of the hull for analysis for the possibility of technological assimilation. Though this was its primary role, it had the added benefit of being a powerful offensive weapon.
The cutting beam had several different power settings namely light, medium and heavy though the last of those three required more power to maintain. (ENT episode: "Regeneration"; TNG episodes: "Q Who?", "The Best of Both Worlds, Part I", "The Best of Both Worlds, Part II"; ST video game: Starfleet Command III)
By 2409 Starfleet, the Klingon Defense Force, and the Romulan Republican Force had reverse-engineered captured examples of the cutting beam, and their own version of the weapon began to appear on some vessels affiliated with Star Fleet Battle Group Omega. (ST video game: Star Trek Online)