Ship Hulls are the main component for building ships, i.e. where you mount your drives so you can deliver your weapons to kill people in different parts of the universe. The hull determines how many of each the ship can hold in a predetermined amount, and how much armor and shields can be used to fill up the rest of the ships layout.

Hybrid hulls can be valuable and interesting, but are harder to research than normal hulls, and rely on random luck mostly.

The hull is the last line of defense in a battle, after the shields and armor. Cannons can score a critical hit on a hull, causing it to blow up before actually taking it down to 0.

The hull is the simplest of the protections. On the ship schematic, it is listed as Hull Mass. In the case of my example, this is listed as 3,069 metric tons. This means that during combat, the hull will absorb an entire 3,069 damage before the ship is destroyed and removed from existance. You do not want to rely on this exclusively, since on smaller ships this is hardly any protection at all (think 3-6 damage). This is basically your final fall-back in case of shield and armor failure.