Synthetic strings are by far the most popular strings among today's players. Pioneered by Thomastik's Dominant string, which have a perlon (a fibre similar to nylon) core, synthetic strings soon superseded steel strings as the choice for many professional and nearly all amateur players. The reasons for using synthetic strings over gut are manifold. Synthetic strings typically produce a more consistent tone than gut and are less susceptible to changes in temperature and humidity. For this reason, synthetic violin strings stay in tune better and have a longer duration. Furthermore, synthetic strings are, in general, less expensive than gut strings.
Traditionally, violin strings were made from catgut (fibres found in the walls of animal intestines, usually sheep or goat), and strings made by this method are still very popular today among many musicians. Gut strings are generally wrapped with metal, usually steel and occasionally copper. Gut strings have a warm, rich sound with many overtones. They take longer to stretch than synthetics, and, once stretched, they are generally stable, but can react to changing weather conditions. Gut strings also require more frequent tuning than synthetic core strings. Different string gauges for gut strings can change the quality and power of tone drastically. Usually a smaller gauge gut string will have less carrying power.
Steel core strings exhibit a bright sound with negligible overtones, good pitch stability (even in changing temperature and humidity), considerable longevity and a more immediate response. Their greater endurance and lower prices mean that metal strings are particularly popular amongst students and beginners; moreover, metal strings are considered the preferred solution for small-size instruments. Nevertheless, many players find the sound quality harsh and coarse, especially when using poor-quality metal strings. It should be noted that steel strings are popular with jazz, folk and country musicians due to their directness of sound.