Steel strings were introduced in the 19th century. They are usually the choice of fiddlers or beginners, and non classical players. These steel strings are likely to produce a thin metallic sound which would seem screechy for most classical players, hence they are generally not used by classical violin players. Steel strings have a clear and bright sound, eliminating overtones. These strings stay in tune for the longest possible time as compared to the other strings and are considered as the most inexpensive ones. Hence, recommended for beginners. Another reason for using steel strings is that it is stable and therefore, easy to learn the basics of playing a violin.
The most popular and well-known brand for steel strings being SuperSensitive Red Label, Jargar, and D'Addario Helicore.
Gut Core Strings
Gut core strings are the most used type of violin string amongst violinists. This is because, these strings are good at producing warm, rich sounds with complex overtones. Gut string is also soft and flexible under the fingers. Now, one is not recommended to use this type of violin string unless you are well accustomed to the tuning and technicalities of playing a violin, as they are harder to tune and create an unstable pitch, which is difficult to control. Hence, usually preferred by professionals. Although the gut strings are the best as compared to other strings, they have certain drawbacks like they have an unfavorable response to climatic changes and humidity, which demands more frequent tuning than before. Plus these strings require at least a week's time to stretch out, before maintaining the tuning stability and cost thrice as much as steel strings.
The most popular brand in this league is Pirastro Eudoxa.
Synthetic strings were introduced in the 1970s; now known as Dominants, made from nylon-perlon. These type of violin strings possess all the qualities of a gut core string but, waives off the disadvantages associated with them. They stretch and stabilize quickly maintaining the tuning stability and is also not affected due to the changes in weather conditions. The innovation of these type of strings has really revolutionized the way violins sound and the use of which is not restricted to professionals only. In fact most of the violin players are seen using synthetic strings, whatever genre of music they play. They are fairly priced and possess a warm and rich sound quality, but with a more stable pitch quality.
The brands worth mentioning in synthetic string league are Dominants, Thomastik Vision, Obligato and Larsen Tzigane.