Los Angeles is the most populous city in California and serves as the commercial, financial, and cultural center of Southern California. It lies within the Los Angeles Basin adjacent to the Pacific Ocean, extending through the Santa Monica Mountains and north into the San Fernando Valley. The city borders the San Gabriel Valley to its east and functions as the county seat and most populated municipality of Los Angeles County.

The area was originally inhabited by the indigenous Tongva people before being claimed by Spain in 1542. On September 4, 1781, settlers founded El Pueblo de Nuestra Señora la Reina de los Ángeles on the village of Yaanga. It became part of Mexico in 1821 and the United States in 1848, incorporating as a municipality in 1850. Oil discoveries in the 1890s and the 1913 Los Angeles Aqueduct drove its rapid expansion.

The city is defined by its sprawling geography and diverse districts, including Hollywood, Venice Beach, and Beverly Hills. Its urban core features Frank Gehry's architectural showcase and hosts the oldest Roman Catholic archdiocese in the United States. The historic center commemorates the original pueblo at Los Angeles Pueblo Plaza and Olvera Street, while the city maintains distinct identities across its numerous neighborhoods and adjacent municipalities.

Los Angeles is a major global hub for television, motion pictures, and music, attracting visitors with its celebrity culture and show business history. The city offers Mediterranean climate conditions and numerous beaches that fostered California's surf culture. It also serves as a host city for the 2026 FIFA World Cup and the 2028 Summer Olympics, drawing international attention to its entertainment and sporting events.

The city proper has a population of 3,898,747 as of 2020. Its economy boasts one of the busiest container ports in the Americas and a gross metropolitan product exceeding $1.295 trillion in 2024. The metropolitan area supports over 18 million residents, while the city itself recorded over 3.6 million visitors in 2023, making it the third-most visited city in the United States.