The different types of strings differ in terms of sound, tuning stability and lifespan. Gut strings are characterized by a soft, warm sound that can be modulated. Synthetic strings are available with different windings and strengths. Depending on the tone and sound that the instruments produce through the bows, a string in strong, medium or soft is used, with medium being the most common strength. Classic properties of steel strings are their insensitivity to temperature and humidity and their long service life.