Twice the fundamental frequency, the frequency is 880Hz. The violin is a stringed instrument with a total of four strings. A2 means that the fundamental frequency is A and the overtone is 2, which is twice the fundamental frequency. The frequency of A5 is 880Hz, which is used to play some high-frequency songs, such as pop music. The violin has a brilliant, flexible and singing tone and has always been very important in Western art music. It has the largest and most famous repertoire of all string instruments, including thousands of concertos.