What are the different types of Fact?

Additive: Additive facts are facts that can be summed up through all of the dimensions in the fact table.
Semi-Additive: Semi-additive facts are facts that can be summed up for some of the dimensions in the fact table but not the others.
Non-Additive: Non-additive facts are facts that cannot be summed up for any of the dimensions present in the fact table. If the columns of a fact table is not able in the position to aggregate then it is called non-additive facts.