Internal styles of martial arts focus on operating from the spirit, mind, Qi/Chi (“energy”) and the use of relaxed leverage rather than muscular power.
The three basic internal martial arts are Tai Chi, Baguazhang and Xingyi which have engendered a variety of lineages and styles.
According to the Journal of Traditional Eastern Health and Fitness, some of the characteristics that differentiate internal martial arts from external martial arts are:
Heightened awareness of internal body posture and structure; release of tension, both externally and internally; letting go of physical, muscular strength to perform techniques and postures; sinking of the “Qi” and the development of “root,” where the center of gravity and origin of movement is lowered within the body; linking of internal organs to assist the flow and movement of “Qi”; and the development of an internal peace or calm emotional state.
Examples of external styles are Shaolinquan, with its direct explosive attacks and many Wushu forms that have flowery aerial techniques.