Shields

Shields are the first and foremost main line of defense for your ship.

Much like your Hull of your vessel, your shields act on a 4 direction basis, damage to your rear only affects your rear shields and once depleted, damage to your rear will affect your rear hull. This is the same with your sides (Port/Starboard) and front. In knowing this, a good tactic to preserve your Hull is to adjust ship orientation once that shield direction has taken a fair batter/blow.

They can't take as much damage before failing as your Hull can, but they can regenerate fairly quickly and unlike your Hull, damage doesn't start penetrating through to your equipment, your Hull is just exposed first after your shields fail.

You pay for equipment damage and hull damage, this is why your shield is the most important defense system on your vessel.