Why are all these tiny ants in m house?

Okay so my brother and I were in the office at our house then he spots so many tiny ants coming in from the door so our office is right next to our front door so he left the office went to the front door and spotted many many more tiny ants, I vacuumed it all but then more starts to come out of these small cracks near the front door, that is the only area they are in. We also have many small ant hole near the garage but it's far away from the front door, so how do I get rid of them, why are they there and would should I do with the any holes?