Violin
The violin is the highest-pitched instrument in the string quartet. It has four strings, which are tuned to the pitches G3, D4, A4, and E5.
Viola
The viola is the middle-pitched instrument in the string quartet. It has four strings, which are tuned to the pitches C3, G3, D4, and A4.
Cello
The cello is the lowest-pitched instrument in the string quartet. It has four strings, which are tuned to the pitches C2, G2, D3, and A3.
The strings of a string quartet are made from a variety of materials, including gut, metal, and synthetic fibers. The type of string used can affect the sound of the instrument, and different players may prefer different types of strings.