Acrobatic gymnastics is a competitive gymnastic discipline where partnerships of gymnasts work together and perform figures consisting of acrobatic moves, dance and tumbling, set to music. There are three types of routines; a 'balance' routine (at FIG grade 5 and above) where the focus is on strength, poise and flexibility; a 'dynamic' routine (also FIG grade 5 and above) which includes throws, somersaults and catches, and (at FIG grade 6 and above, as well as grade 4 and below) a 'combined' routine which includes elements from both balance and dynamic. Acrobatic gymnasts perform in pairs or groups and enter into and are judged at a specific level or age group category. In each partnership, the gymnasts' different sizes and abilities will be balanced to complement each other in order to carry out the complex moves. Some will mainly carry out supporting and pitching roles, and are known as bases. They are then balanced with usually smaller gymnasts who become the 'tops'. In men's and women's groups there is also one or two 'middles', who are like another base who usually will support the top while balancing on the base. (Source: Wikipedia.org, CC BY-SA)