Armor Class

Armor Class is comparable to Dodge in other games. Armor Class helps evade bullets, and even has a secondary, stronger effect, of making snipers aim into your torso, instead of your limbs.

It is important to note, that Armor Class only applies its full effect when running. If the character is walking, only 66% of your Armor Class take effect. When standing still, it is even less, with only 33% of your Armor Class working.

Each 5 points of Armor Class decreases the enemies Hit Chance on you by 1%
Each 5 points of Armor Class increases the chance of an aimed shot to go into the torso instead by 2%

Example

Zmeja has a base (running) Armor Class of 81. A sniper aims at his right arm as Zmeja is standing. He has a hitchance of 87%. (Let's assume the 87% are with 0 Armor Class, even though Zmeja would have had some Armor Class normally in this situation). Zmeja now starts walking, and the Sniper shoots.

What happens in this situation? As Zmeja is walking, 66% of his Armor Class applies. ${\frac {81}{2*3}}$ rounded down, Zmeja has 54 Armor Class. This means, that the Sniper has actually 87%-${\frac {54}{5}}$ rounded down, (87%-10%), so a 77% chance of hitting Zmeja.
However, Armor Class also provides a second effect. ${\frac {54}{5}}*2$, a 20% chance for the shot in the right arm, to instead go into Zmeja's torso.

Both effects would have been stronger, if Zmeja would have ran, instead of just walking. Of course, more Armor Class would be beneficial as well!