The lines and net are the most obvious components of a tennis court. The lines define the area that you must hit the ball within to start and play and ultimately win a point in tennis. Any ball landing outside of the line boundaries is out of play. Any ball within the lines or touching the lines is in play.
Even a ball that barely touches the line is in play. Each line of a tennis court has its own name and function. The lines also form areas on the court which have there own names. Each line is between one and two inches wide
except for the baseline which can be up to 4 inches wide.
It is important to know the line names and areas as other courses will refer to these areas by name.
The line at the end of each side of the court is called the baseline. The baseline extends the full length of the court.
The baseline is one of the boundary of the area of play. Any ball not bouncing before the baseline is out of play. The baseline must also be stood behind when serving.
The baseline is divided in the middle by a center mark, sometimes referred to as the hash mark.
The singles sidelines run lengthwise, perpendicular to the net and forms the other two sides of the outer boundary of the tennis court when playing singles.
The doubles sideline is exactly the same as the singles sideline except that it is not used for a boundary when serving.
The doubles alley is the term used to describe the space in-between the singles side lines and doubles side lines. In singles, or when serving, a ball that lands in this area before bouncing is out of play.
The center service line divides the area between the service lines into halves. This line is always 2 inches wide,
perpendicular to the net and parallel with the sidelines.