Building may be a noun or a verb. Building is one of the most ancient human skills. It is part of how we have survived and it is the clearest symbol of every civilization. Although some other animals build simple structures, e.g. birds, ants and bees, humans have learned to build in a great many different ways to suit different needs and local conditions. We build mostly for shelter. Buildings can shelter people, or animals, or machinery, or anything. The simplest building is just a roof to keep the space beneath dry, or shady. Adding walls gives more shelter, from the wind or rain. It also gives security.