Soft tennis balls fall into two groups: tournament and training. They look similar, but they differ in purpose and price.
Tournament balls are certified — competitions are played with them. They hold an even bounce for longer. If you play matches or want certainty about the parameters, go for tournament balls.
Training balls are cheaper, and for everyday play they perform just as well. You go through a lot of balls at practice, so price matters here. We stock them in white, yellow, black, blue and pink.
Colour is not a whim. White and yellow are the classics, black and blue are easier to see against a light background, and pink is a favourite at kids' sessions.
How many to buy? A dozen is enough to start. A club or academy takes a 120-ball basket, because it works out cheaper per ball and lasts a season.
If you are starting out, take a dozen training balls in a highly visible colour. Add tournament balls for competitions.