About [Defense] and [Block]

[thanhame3 0]

I've been puzzled by this for awhile. The action [block] and [Defense] have appears often, but have i no idea what they mean.

 

From what i think. Block seems to reduce a portion of dmg, i'm not sure how much, and how to calculate this. Is it a fix percentage? Like 25% each time you block for example.

And Defense seems to be happen when you receive 0 dmg from an attack. The question is, does this appear everytime the monster hit you, but their attack is lower than your abs, s o you receive 0 dmg. Or is it that normally, you would receive dmg, let say 100, but when defense happens, you receive 0 from the attack of the same monster?