The South Bay is a region of the Los Angeles metropolitan area, located in the southwest corner of Los Angeles County. The name stems from its geographic location stretching along the southern shore of Santa Monica Bay. The South Bay contains sixteen cities plus portions of the City of Los Angeles and unincorporated portions of the county. The area is bounded by the Pacific Ocean on the south and west and generally by the City of Los Angeles on the north and east.

Greater Los Angeles is the most populous metropolitan area in the U.S. state of California, encompassing five counties in Southern California extending from Ventura County in the west to San Bernardino County and Riverside County in the east, with Los Angeles County in the center, and Orange County to the southeast. The Los Angeles–Anaheim–Riverside combined statistical area (CSA) covers 33,954 square miles (87,940 km2), making it the largest metropolitan region in the United States by land area. The contiguous urban area is 2,281 square miles (5,910 km2), whereas the remainder mostly consists of mountain and desert areas. With a population of 18.4 million in 2024, it is the second-largest metropolitan area in the country, behind New York, as well as one of the largest megacities in the world.