I might hoover over an enemy before my attack, seeing stats like:

I have a base attack of 4.
I have a few buffs/debuffs, so the final attack stat is 5,4.
The enemy has a final defense stat of 4,3.

This equals me making 8 HP worth of damage to my enemy.

Wait, what!
How?

I have no clue what the defense actually does, and I have no clue how the attack/defense calculates the final HP-damage that I inflict.

Does it come later on in the tutorial? Cause I can't find any info regarding combat in Civilopedia, and can't find any wikis or threads about it either :/

Thanks :)

Defense isn't even something you can hoover over to get a tooltip.
Defense is totally ignored in tooltip/help/civilopedia!
Yet it's mentioned everywhere in thet stats - how much defense do the unit have, and what can be done to increase it.
Yet noone knows what it even does???

Takes away quite a lot of the fun, when basic combatcalculations isn't transparent :(

EDIT:
Finally managed to find it, mentioned on https://oldworld.fandom.com/wiki/Units This info should be in the game also, very basic stuff, shouldn't be hidden...