A plow or plough is a machine used for several jobs, including farming and snow removal. It is pushed or pulled across the ground. Human power or other animal power was usual in past centuries; in the 20th century plows are mostly pulled by tractors. The plow lifts up dirt and makes two lines of dirt behind it. The dirt lifted by the plow is more loose than before. Ground that has been plowed is a good place for a farmer to grow food.
Early in the agricultural revolution, simple hand-held digging sticks or hoes would have been used in areas with good soil, such as the area near the Nile River in Africa. At the Nile, the annual flood makes the soil better by rejuvenating it, to create places where seeds could be planted. To help crops grow in areas where floods were rare, the soil had to be rejuvenated in a different way. This is when plowing was first used, and hoes were the first plows.