A plow or plough is a tool or 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 and turns dirt and makes two lines of dirt behind it. Turning the soil buries weeds, brings more nutrients to the top, and loosens the soil. Crops grow better in land that has been plowed.
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.