Meditation is a mental process used to cultivate calm and insight.
On Earth, the Buddhist monks of Tibet meditated every day. (ENT: "Carbon Creek") Meditation was used by Vulcans to calm and keep their tempestuous emotions under control, as part of Surak's doctrine of logic. Certain forms of intense meditation were used to suppress the effects of pon farr when a Vulcan male could not return to his homeworld to take a mate. (VOY: "Blood Fever") Meditation was also used with Vulcan children. (VOY: "Ashes to Ashes")
When he was preparing for college, Jack – a youth from Carbon Creek, Pennsylvania – spent a lot of time at a library doing research about places he would like to visit, including Tibet. While discussing meditation with T'Mir, Jack explained to her that, in his readings, he had learned that the Buddhist monks of Tibet meditated every day. (ENT: "Carbon Creek")
The Vulcan monastery at P'Jem on an unnamed planet included a meditation room where the monks and the landing party from Enterprise NX-01 were held hostage by a commando of the Andorian Imperial Guard in June of 2151. The meditation room also features a hidden passage which leads into the catacombs. (ENT: "The Andorian Incident")
In 2151, T'Pol taught Hoshi Sato, because she had been feeling anxious, a Vulcan meditation technique whereby she closed her eyes and imagined being "on a turbulent ocean" that she herself, however, had control over and could gradually calm. Hoshi at first found the technique was not working for her but, after focusing more, she was amazed by the experience. T'Pol planned to teach her how to employ the technique while alone, an offer Hoshi thanked her for. (ENT: "Sleeping Dogs")
Major Kira Nerys practiced meditation regularly. She once explained to Doctor Julian Bashir that she always needed it after a hard day and that, to meditate, she simply sat quietly. (DS9: "Crossover")
Tuvok once suggested meditation to Seven of Nine for use with a group of Borg children that she was caring for, when she complained to him about the youngsters being unpredictable. (VOY: "Ashes to Ashes")
After the USS Voyager entered a starless region known as the Void in 2375, Tuvok began to meditate in the astrometrics lab before an image of a starfield. He explained to Seven of Nine that he imagined each star as a single thought. (VOY: "Night")