There are a variety of Ant species that can invade your home, property or yard, which include both Red & Black Ants, Acrobat Ants, Carpenter Ants, Field Ants, and dozens more. They are social creatures that infest your home through a variety of entry points (depending on species). But in general, to discourage ant infestation, identity and fix common entry points such as vegetation or handing trees limbs close to your home, cracks and gabs in your walls or flooring. Also, other than searching for places to colonize, they forage for food sources. So storing food and cleaning spills is a great preventative measure for ant infestation. While most of these creatures are considered harmless, there are those – such as fire ants, which sting and carpenter ones, which damage wood – that can be more than a nuisance and pose threats to your family's health and property.
Each species as a different tell tale sign, but unlike other insect species, they don't hide their colonies or their armies, very well. The clearest sign of infestation is seeing an unusual amount of ants or single ants on a consistent basis. Look for mounds in your yard and damaged wood (walls, flooring, cabinets, etc) when in the case of a Carpenter Ant infestation.