An acre is a unit of area commonly used in the United States and other countries to measure land. One acre is equivalent to 43,560 square feet or about 4,047 square meters. It is often used in real estate, agriculture, and forestry to describe the size of a plot of land. The term "acre" has historical roots, originally referring to the amount of land that could be plowed in one day with a yoke of oxen. Today, it remains a standard measurement in various fields, including farming, land development, and environmental conservation.