Energy shielding

Energy Shields are an important piece of technology that protect the users from harm, if only for a short time. Energy Shields, which are generated by MJOLNIR armor or the Elite's armor, provide the user with an extra layer of armor protecting the user against small arms fire. However, the shields will collapse after taking multiple shots. It will protect the user's Health from damage until it is depleted, and it will regenerate after a while, provided that the user is not injured during this time. Be forewarned, although the shield protects your health, it doesn't render you invincible. Pay attention to your shield meter, and if it is depleted, seek cover until it regenerates. Also, it will not protect you from everything, and rockets, grenades, sniper bullets, and some other weapons such as the Needler may shred right through it. Energy shielding is also more vulnerable to plasma-based weaponry (e.g. the Covenant Plasma Pistol, especially overcharged) than to ballistic weaponry (e.g. the UNSC Assault Rifle). Any person can die, no matter how much resistance your shield has, if they are assassinated.

In Halo: Combat Evolved it is shown at the top-right corner of the screen above the health bar, in Halo 2 it is in the bottom-left above the motion tracker, and in Halo 3 the top-center of the screen. They have been changed since Halo: CE by making it charge faster and more resistant.

Human Energy Shielding
Humans started using energy shields with the production of the MJOLNIR Mark V powered assault armor and later the Mark VI. It uses a reverse engineered Jackal Personal Arm Shield that has been modified into a full body shield, much like a Covenant Elite's. Unlike the Covenant Elite Personal Energy Shield, when the human shield takes damage it glows gold. The Covenant ones glow blue. The color difference is speculated to be because of the two technologies being different. Although the shields of MJOLNIR armor are very resilient, they can be stripped in seconds if you're not careful. Plasma weapons are especially effective against MJOLNIR shields. This seems to be a natural weakness of energy shielding. Plasma Rifles, Plasma Pistols, and Plasma Cannons are all very good at depleting the MJOLNIR's shields. The UNSC's most recent breakthrough in energy shield development, came with the creation of the Bubble Shield, which is far superior to MJOLNIR shielding (it would be too expensive to design on the MJOLNIR armor). A larger scale version of the design may provide protection for UNSC Military Bases

Covenant Energy Shielding
Unlike the humans, the Covenant has a very extensive knowledge of shielding equipment and its uses. Examples of this excellent understanding are everywhere. Elite Personal Energy Shields, Jackal Point Defense Gauntlets, Brute Power Armor, Stationary Shield Generators, Portable Shield Generator, Shield Doors, and Starship Shields are just some of the basic examples. The greatest example of the Covenant's understanding is that of body shielding, as all Elites, with the exception of Stealth Elites in Halo: CE, use it.

Also, the Covenant have discovered how to run Active Camo and Shielding at the same time. Even Tartarus and the Prophet of Regret was equipped with a personal shield. Regret's shield, presumably projected by his Gravity Throne, was very similar to the Bubble Shield. It deflected all forms of projectile, plasma, and explosive weaponry and never depleted. It was also similar in that one could simply walk through the shield. It was this that allowed the Master Chief to kill Regret. Tartarus' shield is much different and seems to have to actively turned on. His shield would deflect almost all attacks from the elites, even energy swords, and the only weapon really able to overload it was a beam rifle. It is implied that other brutes have this type of shielding since Cortana says when first fighting brutes on the Gravemind level: "They don't have shield generators, but take them out before.. it's berserking!".

The only known starships to have shields are Covenant ships. All Covenant vessels are protected by a highly resistant energy shield that can recharge over time. Covenant Starship shields are a light-gray color. The shields can take a vast amount of punishment, and can recharge very quickly. They can absorb anything including hundreds of Archer Missiles and even a Shiva nuclear missile (although Shiva nukes will usually deplete their shields, making them vulnerable to MAC and Archer missile fire). The only UNSC weapon capable of penetrating a Starship's Shields is the MAC and nuclear weapons. The only known weakness of Starship shields is that when the vessel fires its plasma weapons, the ship needs to drop a section of its shields for a fraction of a second. It is this weakness that allowed the Spartans to destroy a Covenant ship in The Fall of Reach.

It is odd that the Covenant do not have energy shields on their ground and aerial vehicles, since they are able to make personal energy shields they should have shields protecting their Wraiths, Banshees and Ghosts. Possibly Bungie did not do this to make the game more balanced.

Forerunner Energy Shielding
In all of the Halo campaigns, the player encounters several Sentinels that are equipped with energy shields, possibly suggesting that the Covenant's shielding technology was scavenged from Forerunner technology. Their shields are about equal to an Elite's. The Enforcer is also energy shielded, and can absorb more damage than a normal Sentinel. The shield, which only guards the front area of the machine, is nearly immune to ballistic weapons, similar to the Jackal shield, but is weak against plasma weapons. It is also very strong, capable of withstanding up to three Scorpion shells or two Wraith shots. In the novel, Ghosts of Onyx, a group of Spartan-IIIs encounter a unique type of Sentinel. While other type of shielding are always on, the Onyx sentinel can actively turn on their shield just before contact in order to deflect fast-moving projectile. However, this can be overcome by slow moving projectile such as rocks, and in one case, being boarded by a Spartan. Also Onyx sentinel can combine to make the shield more effective.

Energy Shields in Multiplayer
Like in Campaign shields protect you for a brief amount of time from small arms and weapons. However in Multiplayer, you can have 50%, 100%, 200%, 300%, 400% (Halo: Combat Evolved), 500%, 1000%, 2000% shield, or none at all. Both Elites and Spartans have the same amount of shielding. A player's shields can be further augmented if they pick up a Regenerator or an Overshield. If a player deploys an activated Bubble Shield they will be protected from weapons fire by a spherical energy shield.

The Possibility Of Real Life Shielding
No devices of this kind currently exist in a practical form, although the University of Washington and the Rutherford Appleton Laboratory are exploring separate projects encasing satellites in a plasma "bubble", contained by wire mesh or electromagnetism, to vaporise debris before it can damage the satellite within. The possibility of Solid Light also fits the criteria.

Trivia

 * Contrary to popular Fan and Halo community belief, the Energy Shield is always present, even while not under fire. However, under the stress and strain of projectile resistance when under fire, it glows blue/gold in an electrical design around the wearer's body, eventually giving way due to heavy fire. The Energy Shield is marked as a constant, unwavering protection that covers a Spartan or Elite's entire body, safeguarding the player from any known projectile that isn't more potent than bullets or plasma.
 * It is odd that the Covenant do not use shielding on their ground and aerial vehicles, since they have the technology to have personal energy shields. However, this may be due to the presence of weaponry on the vehicles that would make a shield impractical due to the requirement of dropping the shield to fire.
 * In Halo: Combat Evolved, the shielding that Elites use is slightly stronger than that of a Spartan. Elites' shields only take 70% of the damage that projectile weapons deal out, whereas a Spartan's shielding tends to take the full damage. (Case in point, the Spartan shield, with 75 hit points, only takes three shots from the M6D Pistol to break, whereas a Minor Elite's shield, which has 100 hit points, takes 8 shots from the same weapon.) Apparently this was changed in Halo 2 and 3 - in Halo 2, it takes four bursts from a Battle Rifle to break both a Spartan's shield and a Minor Elite's shield. But the fact that when testing the Hit Point of the Master Chief in the campaign at normal(which is considered canon) the MC as a lot more health than on multiplayer(heroic in halo 2 and 3).
 * It is never fully explained what happens to the Plasma bolts or Bullets when they make contact with the Energy Shield, but it is likely it absorbs or even vaporizes them.
 * In Halo 3, in Campaign, the energy shields of The Arbiter and Shielded Flood Combat forms do not flare when taking damage. However, other Elite's shields still flare when taking damage.
 * In Halo Wars, many ground vehicles have shields, including Ghosts, Wraiths, and Locusts.

Related Pages

 * MJOLNIR Armor
 * Elite Personal Energy Shield
 * Jackal Point Defense Gauntlet
 * Bubble Shield
 * Overshields
 * Regenerator
 * Stationary Shield Generator
 * Portable Shield Generator