As by history of any sport, it is hard exactly to say when was tennis invented. Most sources says that it was French monks in the 11th or 12th century who played something similar to todays tennis. To comparison to todays tennis, instead of racquets, they used they own hands. Later, it was wooden paddle, that was used. In 14th century, players had begun using racquets that are near to todays, built from strings made of gut bound in a wooden frame. Later, the the basic material for construction of racquets, became graphite. Since first usage of graphite, the new racquets are constructed to be lighter on weight. Producers are trying to use many new materials like ceramics, fiber or titanium, but the final products if always a composite with graphite.
Photo Credit: Petr Kratochvil