The game of tennis dates back several hundred years, originally invented by European monks as a form of entertainment during religious ceremonies. In these early games, players hit the ball with their bare hands. The game evolved over the years and gained immense popularity amongst Europe's nobility, especially in France, where the royal family adopted the game. By the 1870s tennis as we know it today had come into being, and table tennis, its miniaturized version, emerged as a popular parlor game for the upper middle class. In the 20th century, game manufacturers began to market table tennis sets, also known as ping-pong for the sound of the ball hitting the paddles, so that families could enjoy the sport indoors. Table tennis maintained its popularity over the years and became an official Olympic sport in 1988.