Comparing the goals, teaching methods, and techniques of different fighting systems can help us understand their similarities and differences, but comparisons are often controversial when there are no one-to-one correspondences between systems. Many martial arts systems have spiritual or philosophical goals as well as combat training goals. Chinese, Japanese, and Korean martial arts emphasize traditional Confucian philosophy and teaching methods. Sports-oriented systems such as judo, taekwondo, and wushu have their own rules, many of which are incompatible with those of other systems. Some "reality-based" schools, as they are called, focus on self-defense. These schools include Jeet Kune Do, Defendo, Krav Maga, Kombato, and Angeles Eskrima. Because different schools often have different goals, it is difficult to compare the effectiveness of their methods. For example, it is impossible to compare Kendo against taekwondo.

However, comparisons may be made to some extent within a specific context or category, such as weaponless combat between two fighters, self-defense against multiple assailants, the use of a specific weapon, escaping from pursuers, and so on. Regardless of the martial arts system that individual participants practice, those sharing an interest in hand-to-hand combat might compete, using an agreed-upon set of rules, to see who is the better fighter. In the 1990s, the Ultimate Fighting Championship, or UFC, in the U.S. held a martial arts tournament to answer the question of which fighting system was the best. As few rules as possible were used. Due to the increase in mixed martial arts practice, such organizations as this have arisen to answer the question.

Followers of mixed martial arts systems, or MMAs, an eclectic form of martial arts cross-training, believe that no traditional fighting system is fundamentally better than another. They believe that one can become a better fighter overall by being competent and well trained in multiple systems. Tournaments such as those held by the UFC and Pride Fighting Championships emphasize competition between individuals rather than competition between specific systems. Almost all participants are skilled in the techniques of multiple systems.

MMA is seen basically as a form of sports competition with rules specific to different organizations, but it could also be seen as a school of thought in itself in which individuals can incorporate any useful martial art technique into their personal style. MMA competitive fighters incorporate traditional techniques from boxing, wrestling, Muay Thai, jujutsu, and other disciplines while using an overall strategy of fighting, such as "sprawl-and-brawl" or "ground-and-pound." These complex, modern fighting styles could be described as a natural evolution of the martial arts.