Alcatraz is a small rocky island in San Francisco Bay, in California, in the United States. For years it held a famous federal prison, known for very strict rules and for being almost impossible to escape from. In most heads the name now means that prison. Films have turned it into a legend. People also use it as a comparison: a workplace, a school, or another jail that feels impossible to leave may be called 'like Alcatraz'. Though actually, the name itself is about sea birds, not demons — it comes from a Spanish name for an island of gannets. Before the famous prison it was a fort and a military jail. The prison closed in 1963; the island is now a tourist site. In English it is a proper name. It feels heavy and grim — not a word for any ordinary local jail.