Ska punk is a fusion music genre that combines ska and punk rock. It achieved its highest level of commercial success in the United States in the late 1990s. ska-core (sometimes spelled skacore) is a subgenre of ska punk, blending ska with hardcore punk. The characteristics of ska punk vary, due to the fusion of contrasting genres. The more punk-influenced style often features faster tempos, guitar distortion, onbeat punk rock-style interludes (usually the chorus), and punk-style vocals.