Tennis matches are supposed to be played without lengthy pauses. In general, a serve needs to occur before more than 20 seconds has passed since the end of the last point. This turns into 90 seconds when the players switch sides of the court (every odd total of matches) and 2 minutes between sets. Besides these cases, breaks are only allowed when the cirumstances are beyond the players' control (rain, errant ball, damaged racket, etc.). At the end of the match, convention says that players must shake hands.
Matches are generally played by gender. Females play against females and males play against males. In unprofessional matches or in players' free time, they might play a mixed game, where there is a female and a male playing against another female and a male or a male against a female. There can be any combination of set ups for this.
Tournaments are organized by number and gender. The structure of tournaments are organized by men's singles, women's singles, men's doubles, and women's doubles. In the four Grand Slam tournaments, each section can only have 128 people of each gender. Most tournaments set players up so that the best players don't meet until later in the tournament (seeding), but it is possible that a tournament will set players up by their skill levels.
The Grand Slam tournaments are considered the most prestigious tennis events in the world. They are held anually in a certain order:
Besides their historical significance, these tournaments have larger amounts of prize money and are worth twice the number of ranking points. In the Grand Slam men's tournaments, they play a best-of-five set match, and in the women's Grand Slam tournaments, they play a best-of-three set match.