Trap is a subgenre of hip hop music that originated in the Southern United States, with lyrical references to trap starting in 1991 but the modern sound of trap appearing in 1999. The genre gets its name from the Atlanta slang term "trap house", a house used exclusively to sell drugs. Trap music uses synthesized drums and is characterized by complex hi-hat patterns, snare drums, bass drums, some tuned with a long decay to emit a bass frequency, and lyrical content that often focuses on drug use and urban violence.