Natural gut strings are made of cows' or sheep's gut in a very complicated process. Their main features are excellent elasticity, great tension stability and liveliness. But they are very expensive and sensitive to weather, while I must say that a lot of improvement has been made in this direction during the past few years.
Natural gut is still the most playable string among the pros, lately specially used as cross combination with polyester string- hybrids.
Examples: Pacific Prime Gut, Pacific Tough Gut, Babolat VS Team, Klip Legend, Bow Brand Championship.
Nylon string is the most common used string type. These strings are among the most reasonable and most recommended tennis strings around the world.Strings are normally made of a single nylon core and various resistant wraps. Because of its special dynamic properties nylon (polyamide) is well suited as a material for tennis strings. High number of different types of constructions (wrap material and wrap angle) influences the string's playing characteristics. Nylon strings with multiple wraps can be considered higher grade than single wrap nylon strings. The wraps reduce the tension loss usually experienced with nylon strings. Nylon strings are suitable for players who have normal or high string consumption.
Examples: Pacific Power Line, Wilson Championship Nylon, Babolat Powergy, and Prince Tournament Nylon.
Polyester strings show us a pretty simple structure. They are made of a single polyester fiber with thin one or more coatings. This type of construction is named - monofilament. They come in different gauges (1.10-1.35mm) which enable you to choose among different elasticity/durability levels. Polyester strings are little elastic and feel quite stiff compared to nylon or multifilament strings, but on the other hand they provide significantly better durability, allowing for thinner gauges. Polyester strings have one main bad side. They tend to lose their tension quite quickly, so control decreases and the string feels dead after a short time of play.
Polyester strings are only recommendable for players with high string consumption. For these players, polyester strings offer a great price/performance ratio. During the past few years, tremendous effort has been put into the advancement of monofilament strings and the elimination of their major weaknesses (tension loss and lack of elasticity). More and more polyester blends (co-polyester), mixed with a number of other materials like PEEK, carbon or metallic fibers, and are being developed to modify the playing characteristics. Almost every manufacturer carries such strings in their program today.
Examples: Pacific Poly Force Extreme, Luxilon Big Banger Alu Power, Kirschbaum Touch Turbo, Head Ultra Tour.
This string is designed as close to natural gut as possible and because of that these strings cost more than nylon strings, as the manufacturing process is very complex. Many microfibers are twisted together to a string, which is wrapped with a resistant cover. Multifilament strings have high elasticity and great playability and are on the highest level of tennis strings performance. Main bad side - multifilament strings tend to break soon once the resistant cover is damaged.
Examples: Pacific Futura TXT, Babolat XCel Premium, Isospeed Professional, Head FiberGel, Kirschbaum Touch Multifibre, Wilson NXT Tour.
These strings are designed to provide better ball grip. Most of these strings present great spin potential in line with great control. But the texture usually holds only for a short time and the strings become smooth.Another bad side is their short durability.
Examples: Pacific Power Spin, Kirschbaum Super Smash Spiky, Isospeed Pyramid, Prince Topspin Plus.
Pretty new strings on the market are Hybrid strings. But they manage to convince a lot of players in a very short time, so in the moment almost 80% of tour players are playing hybrids. This string is combination of two different strings for mains and crosses. On the racket it is almost always a main string that breaks. This is because the main strings move a lot more than the cross strings so the cross strings "saw" into the main strings, causing notches and eventually breakage. That's why in hybrid strings usually a durable string is used as the main string (polyester, aramid/kevlar). As cross strings usually highly elastic synthetic strings or natural gut strings are used to provide comfort and feel. Hybrids provide excellent playing characteristics while a poly/multi hybrid often lasts longer than a pure poly or pure multifilament string job. There are an almost infinite number of possible string combinations, as you can create highly individual combinations. There are also some pre-packaged hybrids available from the major string brands.
Examples: Pacific Poly Gut Blend, Wilson HyperLast. Babolat offers the possibility to obtain "half" sets of the Pro Hurricane, the X-Cel Premium and the VS Team for individual combination (Custom+ Hybrid).
How to Select Racquet Strings
General tips about strings