The Grapple Beam is one of Samus' many power-ups that allows Samus to grip distant surfaces, and swing her self onto a different platform.
The Grapple Beam, which first appeared in Super Metroid, has appeared in mostly all of the Metroid games that succeeded it. In Metroid Prime, and Metroid Prime 2: Echos, the primary use of the beam is to swing long distances to get to new areas. In Metroid Prime 3: Corruption, it was also given the ability to pull objects as well. For example, pulling an object away from blocking a door, or a sheild from an enemy. In every 2D Metroid game the Grapple Beam is featured in, it is fired out of the arm cannon. In every 3D Metroid game, however, Samus is given a glove that allows her grapple. Additionally,It is featured in every single Super Smash Bros. game to date, and giver her the ability to throw her oponent.
The basic function of the Grapple Beam is to allow Samus to swing from platform to platform. This is most apparent in every Metroid game from Super Metroid to Metroid Prime 2: Echos. In Metroid Prime 3: Corruption, the Grapple Beam is given upgrades, with which comes more functionality.
1.Grapple Beam - Gives Samus basic swinging abllities.
2. Grapple Lasso - Gives Samus the ability to lock onto enemies and rip objects from their hands. Additionally, It can be used on items to bring them to a reachable range.
3. Grapple Voltage - Allows Samus to transmit energy into the enemy or object.
4. Hyper Grapple - The fourth and final upgrade, allows Samus to push phazon into the bodies of her enemies while obsorbing it at the same time causing critical damage on many enemies.
Samus' Gunship can also obtain a Grapple Beam that allows her ship to transport large objects from one location to another.