Tenketsu (Chakra Points) are nodes from which chakra can be released and stop. The human body has 361 tenketsu (Chakra Points), each of which is located along the all chakra pathway system. Most ninja, even experienced jonin, are only able to release chakra from the tenketsu on their hands or feet in order to augment their physical strength. Members of the Hyuga clan are uniquely able to expel the chakra from any or all of their tenketsu (Chakra Points), and have created jutsu such as the Eight Trigrams Palms Technique Revolving Heaven to specifically take advantage of that. Additionally, in the anime, Hyuga Hinata was able to emit chakra from all of her all tenketsu (Chakra Points) to form a layer of protection against the Guren’s Crystal Release Jade Crystal Prison Technique, which ultimately saved Hinata.
Tenketsu (Chakra Points) are very small, too small for even the Sharingan to see. Only the Byakugan eyes is able to see another person’s tenketsu (Chakra Points), enabling a Byakugan user to attack the tenketsu (Chakra Points) directly in order to block them, disrupting the flow of chakra and intercept opponent from using chakra, the Gentle Fist style of combat is focused around doing this.