Situated at the northern tip of the San Francisco Peninsula, San Francisco—officially known as the City and County of San Francisco—is the commercial, financial, and cultural hub of Northern California. In addition to parts of Alameda Island, Red Rock Island, and Angel Island, the city includes scenic islands such as Treasure Island, Yerba Buena Island, and Alcatraz. The city also includes the uninhabited Farallon Islands, which are located in the Pacific Ocean 27 miles offshore. San Francisco, which is named for its "seven-by-seven-mile square" layout, is around 232 square miles in total, encompassing land and water, with 46.9 square miles of land at the tip of the peninsula.

The Pacific Ocean's currents contribute to San Francisco's chilly summers and mild Mediterranean climate. It has very little temperature variance and chilly winds, especially in the summer months when it is typically foggy. The temperature in the city rarely rises beyond 80 °F, with cooler weather from November to April and a dry period from May to October. The average annual precipitation varies significantly from 23.65 inches. Due to its coastal location, San Francisco is likely to experience rising sea levels due to climate change. The city is located in USDA Plant Hardiness Zone 10b, with certain parts of the downtown approaching Zone 11a.

San Francisco's array of parks, including those within the Golden Gate National Recreation Area, attracts over 13 million annual visitors. Ocean Beach and Baker Beach are popular for their Pacific Ocean views and vibrant surfing scene. The historic Presidio, now a sprawling park, features museums and Crissy Field's restored marsh. Other notable sites, like Fort Funston and Alcatraz, are administered by the Golden Gate National Recreation Area. The city manages 220 parks, with Golden Gate Park as a prominent cultural and natural hub. San Francisco's commitment to accessible parks is reflected in its ranking as the fifth-best city in the U.S. for park access and quality, ensuring a park within a 10-minute walk for every resident.

Numerous universities, including the University of California, San Francisco, which specializes in health and biomedical sciences, are located in San Francisco County. The University of San Francisco, the oldest university in the city, was established in 1855. About 30,000 students can be accommodated at San Francisco State University, which is a component of the California State University system. Renowned art colleges like California College of the Arts, San Francisco Art Institute, and Academy of Art University are also located in the city. The San Francisco Unified School District, which runs 114 schools, including renowned establishments like Lowell High School, is in charge of primary and secondary education. Approximately thirty percent of those who are of school age attend private or parochial schools, while the Archdiocese of San Francisco oversees approximately forty Catholic institutions. Nearly 300 preschool programs are available in the city, and the Preschool for All initiative provides universal preschool access for four-year-old children.

Over 32% of people in San Francisco County use public transportation, mostly the San Francisco Municipal Railway (Muni) and the famous cable cars, which make up the county's extensive transportation network. While boats like the San Francisco Bay Ferry and Golden Gate boats provide waterway transit, the city is connected to other areas by the Bay Area Rapid Transit (BART) system. Through programs like Bay Wheels, the city promotes bicycling, and the Vision Zero strategy outlines its commitment to safety precautions. The second-most walkable city in the US is San Francisco, which is home to the main hub San Francisco International Airport (SFO) and places a high priority on pedestrian-friendly infrastructure.