Dmg types? (slashing, blunt, and what not)

I know this is kind of silly to ask after playing for a month now, but what exactly is the significance of the damage types? If there is any, can someone give me the breakdown of what they do? I've already used the search button and came up with nothing. Thanks in advance.

I'm not certain about the other classes, btu I know rangers can get armor that is better against piercing damage