Los Angeles County, officially the County of Los Angeles, and sometimes abbreviated as L.A. County, is the most populous county in the United States, with 9,861,224 residents estimated in 2022. Its population is greater than that of 40 individual U.S. states. Comprising 88 incorporated cities and many unincorporated areas within a total area of 4,083 square miles (10,570 km2), it is home to more than a quarter of Californians and is one of the most ethnically diverse U.S. counties. The county's seat, Los Angeles, is the second most populous city in the United States and the most populous city in California, with 3,822,238 residents estimated in 2022. It is also known for being the home of the American film and television industry, a distinction it has held since the early 20th century which has given the county global prominence.

Los Angeles, often referred to by its initials L.A., is the most populous city in the U.S. state of California. With roughly 3.9 million residents within the city limits as of 2020, Los Angeles is the second-most populous city in the United States, behind only New York City; it is also the commercial, financial and cultural center of Southern California. Los Angeles has an ethnically and culturally diverse population, and is the principal city of a metropolitan area of 13.2 million people. Greater Los Angeles, which includes the Los Angeles and Riverside–San Bernardino metropolitan areas, is a sprawling metropolis of over 18 million residents.