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 him against small arms fire. The shields however 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).

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 first began using energy shields with the production of the MJOLNIR Mark V powered assault armour 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 armour 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.

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 Starships shields are a light-grey 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. One of their primary advantages is a gold-colored Energy Shield that is completely resistant to all projectiles much like the UNSC Bubble Shield; however, it shares the same weakness: slow moving projectiles (such as rocks, people, and vehicles) pass straight through it. In Halo 3, Sentinel shields look like they are made up of many small hexagons, similar to that of a Bubble Shield.

Energy Shields in Multiplayer
Like in Campaign shields protect you for a short, 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 players shields can be further augmented if they pick up a Regenerator or Overshields. 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
Currently no shielding of this kind exists. Kevlar, a tightly woven anti-ballistic fabric that is used to stop bullets from penetrating the body, and Boron carbide, a powerful and light material are the only plausible protection for troops. But tests have recently shown that plasma can create a sort of "barrier" against possible projectiles although much more testing still must be done. Also using an electro-magnetic field, you can possibly shape an energy field to deflect projectiles. But the tremendous energy consumption has no current possible way of being supplied.

Trivia

 * Contrary to popular Fan and Halo community belief, the Energy Shield is present while not under fire. However, under the stress and strain of projectile resistance when under fire, it glows white 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 arial vehicles, since they have the technology to have personal energy shields.

Related Links

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