There are three main ways of studying fighting: no-contact, semi-contact and full-contact. No-contact way trains the practicer to learn rythm and distance. Semi-contact way is used to develop a strategy of attack and defence without hitting with full power.
Full-contact is a free way of fighting: the practicer must use everything he/she learned and it is allowed when the practicer has reached a high degree of control of his/her movements and of resistance to pain.