A type of music characterized by it's cacophonous wall of sound and accelerated tempo which is achieved through distorted electric guitars playing fast-paced riffs, with the driving drumbeat often utilizing hypersonic double bass rhythms and emphasizing the continuous pumping action, the bass guitar is often playing similar to the guitar, but more with the drums, so as to add to the overall heavyness and depth. It can manifest in many different forms and the spectrum of intensity is usually quite varied. From slow and heavy melodic grooves, to complex and precise blinding rhythms, odd time changes, and sheer brutality.. metal comes in many shapes and sizes. One common trait of metal is to have vocals dealing with dark subject matter, often sung with anger, aggression, and conviction in the form of screaming. Melodic smooth vocals are also accepted. Solos are an integral part of metal music, as the icing on the cake to complement the heavy intensity of the songs and add more depth and individuality. Real metal has a solo in every song, usually scales and arpeggios played with some changes often in 8th, 16th, or 32nd notes..if only a few quick licks. Metal is progressive and dynamic, and usually provokes feelings that are therapeutic to the listener. Metal is rock music that has evolved.