Strings (tennis)
In tennis, the strings are the part of a tennis racquet which make contact with the ball. The strings form a woven network inside the head (or "hoop") of the racquet. Strings have been made with a variety of materials and possess varying properties that have been measured, such as dynamic stiffness, tension retention, thickness (gauge), string texture (shape of the string), and rebound efficiency.
Guqin
Until recently, the guqin's strings were always made of various thicknesses of twisted silk, but since then most players use modern nylon-flatwound steel strings. This was partly due to the scarcity of high quality silk strings and partly due to the newer strings' greater durability and louder tone.