Until the late 1970s, the ruling authorities in tennis saw no need to set parameters for the size of rackets. From the sport's earliest days rackets were similar in shape to those in use today. While manufacturers had their own preferences in terms of weight, strings and strength, there was little difference in the general style. Frames were mostly made out of ash, although newly developed adhesives and the ability to fashion thin veneers enabled manufacturers to use other woods from the middle of the last century.
Manufacturers had long experimented with metal frames, but the problem of threading tensioned strings through the sharp edges of holes was not resolved until the invention of the Wilson T2000 racket, on which the strings passed through metal wires secured to the frame. The racket was pioneered by Jimmy Connors, who won Wimbledon with it in 1974. At about the same time manufacturers started to experiment with composite frames, which was made possible by the development of carbon fibre (also known as graphite). By the early 1980s the wooden racket was heading for the museum.
Carbon composite frames have now become the norm. Compared with the wooden rackets of the 1980s, they are stiffer and lighter and have bigger heads, with subsequently larger "sweet spots". It was when manufacturers started producing rackets with significantly larger heads – Prince's "oversize" head was especially popular – that the International Tennis Federation decided in 1979 to set limits on sizes.
The first tennis rackets were strung with natural "gut", using the flexible outer skin of animal intestines. Synthetic strings, made out of nylon, polyester or Kevlar are now widely used. Modern frames also make possible string tensions that are almost double those that were used with wooden rackets.