Carpenter ants are very common near the wood structures. They got their name from their habit to build burrows inside the wood. They make holes inside the wood which causes damage to the wood and structures made out of it. Carpenter ants can bring a significant risk to your house as their population can multiply fast.
If you notice large, wingless, black ants inside the house, it indicates ant infestation. This doesn't always mean that a nest is present inside the building. The nest can actually be located outside, near the building. In that case, worker ants are probably visiting in search of food.