Tennis is a game played between two players (singles) or between two teams of two players (doubles). Players use a stringed racquet to strike a hollow rubber ball covered with felt (most of the time yellow, but can be any color or even two-tone) over a net into the opponent's court.
Tennis is played on a rectangular, flat surface, usually grass, clay, or a hardcourt of concrete and/or asphalt. The court is 78 feet (23.77 m) long, and its width is 27 feet (8.23 m) for singles matches and 36 ft (10.97 m) for doubles matches.[20] Additional clear space around the court is required in order for players to reach overrun balls. A net is stretched across the full width of the court, parallel with the baselines, dividing it into two equal ends. The net is 3 feet 6 inches (1.07 m) high at the posts and 3 feet (914 mm) high in the center.
网球是一项隔着球网、用球拍击打橡胶制空心球的运动。网球起源于英国，最早流行于英语国家的上流社会。网球分单打和双打。乒乓球起源于网球。
网球比赛在一个长方形的场地上进行。网球场地上用白线划出界线。标准网球场的长度是23.77米（78英尺）。单打比赛的球场宽度定为8.23米（27英尺），双打比赛则为10.97米（36英尺）。球场左右两旁的线则相应地称为“单打边线”或“双打边线”。球场两端的白线称为“底线”。两条底线的中间标有短小的中界点。球场周围必须留出空间。
球网与球场的底线平行，穿越整个球场，将球场分为相等的两部分，因此球网与两条底线的距离各为11.89米（39英尺）。球网两端悬挂在两边的网柱上。网柱中心在双打边线外的91.4厘米（3英尺）处。球网在网柱处的高度为1.07米（3英尺6英寸），在球场中央的高度则是91.4厘米（3英尺）。球网顶部用白色网边布包缝。
参考资料：Wikipedia