Natural Ventilation (passive):
Natural ventilation is the process of supplying and removing air through an indoor space by natural means, meaning there is no forced ventilation. An example of this would be opening a window to get some fresh air inside the home.
You typically put as much fresh air into the house as you push out. This through central ERV or HRV systems.
A fan suctioning "dirty" air out of the house, typically found in bathrooms and kitchens.