California is a state spanning the southern half of the west coast of the contiguous United States. With a population of 37 million and an area of 158,402 square miles, California is the largest U.S. state in population and the third largest in area.

The region was inhabited by Native Americans before European explorers started to make sporadic visitations during the 16th century. California had the highest density and greatest diversity of indigenous peoples in what is now the United States. Spain colonized the coastal areas of the territory starting in 1769. As a result of the Mexican War of Independence, California became a part of the Mexican Republic in 1821. It was captured by the United States in the Mexican-American War (1846-1848) which was concluded with the Treaty of Guadalupe Hidalgo. The California Gold Rush of 1848-1849 brought about 90,000 additional U.S. immigrants into the state, and California became the 31st state of the Union in 1850.

Although the state's sunny climate has given it a historic reputation for being laid back compared to the East Coast, the $1.55 trillion (as of 2005) California economy is larger than all but the top 7 national economies in the world and is responsible for 13% of the United States' $13 trillion gross domestic product (GDP). The state's major predominant industries include agriculture, entertainment, light manufacturing, and tourism. California is also the home of several significant economic regions such as Hollywood (entertainment), the California Central Valley (agriculture), Silicon Valley (computers and high tech), and the Wine Country (wine).