Thickness: The thicker the string, the lower the pitch it will produce. This is because thicker strings have more mass, which makes them vibrate more slowly.
Tension: The tighter the string is stretched, the higher the pitch it will produce. This is because tighter strings vibrate faster than looser strings.
Material: The material of the string also affects the pitch of the sound it produces. Different materials have different densities and elastic properties, which cause them to vibrate at different frequencies.
In general, low-pitched sounds are produced by long, thick, tight strings made of materials with a low density and high elasticity. High-pitched sounds are produced by short, thin, loose strings made of materials with a high density and low elasticity.