Nèi jiā, literally "internal family", is a term in Chinese martial arts, grouping those styles that practice
nèi jìng, literally "internal strength", usually translated as internal martial arts, occupied with spiritual, mental or qi-related aspects, as opposed to an "external" wài) approach focused on physiological aspects. The distinction dates to the 17th century, but its modern application is due to publications by Sun Lutang, dating to the period of 1915 to 1928.
Nèi jìng is developed by using nèigōng, or "internal exercises," as opposed to wài gōng, "external exercises."
Nèijiā is a broad term used mistakenly in the West as a synonym for the more specific Wǔdāngquán styles, named for their association with the Taoist monasteries of Wudangshan range, Hubei Province in Chinese popular legend. These styles are enumerated by Sun Lutang as Tàijíquán, Xíngyìquán and Bāguàzhǎng, but must also include Bājíquán and the legendary Wudang Sword. Some other Chinese arts, not in the Wudangquan group, such as Liuhebafa, Bak Mei Pai, Bok Foo Pai and Yiquan are frequently classified (or classify themselves) as "internal".