Can somebody please explain HP to me?

Im not quite sure what it is compared to defence.

HP (Hit Points) is a stat every unit has. When you attack an enemy unit(s) the amount of attacks that you dealt is subtracted by the amount of total HP of unit(s) you attacked. On the other hand, the unit(s) you attacked will also defend since they are in a defensive position. The total defense of those units will diminish the amount of HP of your units. In the end of the battle, when a unit is left with 0HP it is destroyed.

Here's an example (follow the instructions from 1-6)


YOU (the attacker)
ENEMY (the defender)

1) 2 tanks (YOU)
1) 1 militia (ENEMY)
2) total attack roll of both tanks: 10
2) total defense roll of both militia: 3
3) So after the rolls it is 10 attack VS 3 defense
4) Also keeping count that all units in the game of 7HP that means that you have 14HP (2*7) and your enemy has 7HP since he only has 1 unit heading in to battle
5) So, since you're the attacker your total attack roll, which is 10 will be subtracted by the amount of HP of enemy units. (10 - 7) leaving you with 3 attack and your enemy with
0HP which means his militia dies.
6) On the other hand, if your total attack roll wasn't high enough to destroy the militia, your enemy's unit would have made defensive damage of 3 against your 14HP leaving you with 11HP and killing him off in the next round.

So that is how the HP system works. I hope i didn't confuse you too much but I'm sure you'll get it eventually. The system can also vary depending on the strategy you're using. Strategies such as Iron Fist and GC will have a different outcome in battles and so forth.

Here's a link to the FAQ about the battle mechanics.

http://afterwind.com/home/faq.php?faq_id=17

In a simpler way HP is what makes units get Muscular