Competitive dance is a sport in which competitors compete in a range of dance styles before a panel of judges, including acro, ballet, contemporary, jazz, hip-hop, lyrical, modern, musical theatre, tap, and improv. Dancers compete in various activities, including pom squad and dancesport, for a specific goal or for specific dance genres or styles (competitive ballroom dance). The two main players in the competitive dance sector are competition production companies, often known as dance competition companies, and dance competition lines, which organize regional events at stops along their annual, cross-country tours. Students from five to eighteen years old can compete in a number of regional events. Most schools compete at the national level toward the conclusion of the season after competing at the regional level. Dance schools—more often known as dance studios—hold competitions for their classes. For more difficult routines, advanced dancers can do solos, duets, trios, or small group routines in addition to or instead of larger group routines. In general, tournaments start in January and last until July or August. Because even brief dances can be physically demanding, dancers who compete must be in good physical shape. Along with maintaining their strength, flexibility, and sense of balance, dancers must always improve their technique. Dancers are strongly advised not to take any activities that could put them at danger for injury or illness, especially when competing. Except for holidays and summer vacations, competitive dancing is normally a year-round passion. Dancers take classes to hone their routines during competition season, and they also take classes off-season to prepare for the following competition season. To hone their techniques, lots of dancers go to summer intensives.