From Halopedia, the Halo wiki
Gravitics is the science and technology of generating and manipulating gravity. This science is employed by the Forerunners, Covenant and Humanity alike, with common applications including Anti-gravity technology, lenses to precisely focus energy and presses for manufacturing highly compressed forms of matter.
Gravitic technology is commonly employed in weaponry, with the Jiralhanae (especially the Banished) employing the use of gravitic accelerators, or "gravitic catapults", for the operation of their Spike weaponry. The Forerunners employed specialised weapon systems aboard their spacecraft such as the torsion driver, designed to use gravity to rip spacecraft apart and subject their innermost components to concentrated fire from directed energy weapons. Pulse laser weapon systems employed by the Covenant use gravitic-lensing focal arrays, and energy projectors employ the use of gravitic impellors to create their plasma beams. The Covenant employ gravitic webs inside their drop pods to protect their occupants from sudden deceleration, a technology similarly mimicked inside some UNSC armor systems including the AVIATOR-class Mjolnir. The Halberd-class destroyer employs gravitic technology to accelerate/ decelerate small craft such as space fighters and dropships.