Martial arts are systems of codified practices and traditions of training for combat. While they may be studied for various reasons, martial arts share a single objective: to physically defeat other persons and to defend oneself or others from physical threat. In addition, some martial arts are linked to beliefs such as Hinduism, Buddhism, Daoism, Confucianism or Shinto while others follow a particular code of honor. Many arts are also practiced competitively, most commonly as combat sports, but may also take the form of dance.

The term martial arts refers to the art of warfare (from Mars, the god of war). It comes from a 15th-century European term for fighting arts now known as historical European martial arts. A practitioner of martial arts is referred to as a martial artist.

In popular culture, the term martial arts often specifically refers to the combat systems that originated in Asian cultures, especially East Asian martial arts. However, the term actually refers to any codified combat system, regardless of origin. Europe is home to many extensive systems of martial arts, both living traditions (e.g. Jogo do Pau and other stick and sword fencing and Savate, a French kicking style developed by sailors and street fighters) and older systems of historical European martial arts that have existed through the present, many of which are now being reconstructed. In the Americas, Native Americans have traditions of open-handed martial arts including wrestling, and Hawaiians have historically practiced arts featuring small- and large-joint manipulation. A mix of origins is found in the athletic movements of Capoeira, which African slaves developed in Brazil based on skills they had brought from Africa.

While each style has unique facets that make it different from other martial arts, a common characteristic is the systemization of fighting techniques. Methods of training vary and may include sparring (simulated combat) or formal sets or routines of techniques known as forms or kata. Forms are especially common in the Asian and Asian-derived martial arts.