Shields are a way to defend your ships. They are charged using booster kits, and take damage from attacks. An (incomplete) list of all shields is available in the shields category. Shields all have energy, skills and captain level requirements so always check before purchasing.
Shields are solely for Combat. You equip them to be able to sustain more damage in a fight. The main advantage shields have over Hull and Armour is that you can recharge your shields during a fight by using Matrixes. The main disadvantage is that some enemies use missiles that bypass your shields completely.
Shields are separated into three main types: reflective, absorption and phased.
Uses "polarized hull plating", in effect an energy charge applied to a ship's hull to make it more resistant to weapons fire.
Absorption as a general rule sits in the middle between Reflective and Phased shielding. The Absorption shield system when charged shapes the shield to meet incoming fire power, reinforcing the weakest elements of the shield. Once the shield has established a field, any energy fired at the shield is then absorbed into the in-line capacitors.
Shields operate by emitting a layer of energy distortion containing a high concentration of gravitons around the object (such as a ship or city) to be protected. Shield energies can be emitted from a localized antenna or "dish" (such as a ship's navigational deflector) or from a network of "grid" emitters laid out on the object's surface (such as a ship's hull).
While an alien shields skill exists, no known alien shields are available for purchasing yet.
Which type for me?
The difference between reflective and absorption is that absorption shields have a lower requirement on the captain's level, whereas reflective shields have a lower IP requirement. So if you plan on pursuing a career in combat, absorption is your way of getting the most shielding at your level. In contrast, if you wish to use your IP for other purposes, reflective shielding is your type.
Once you get to the Expanse, both reflective and absorption are useless. You need at least phased shielding, or perhaps alien shielding if and when they are released to the public.