"The seven-year cycle is biologically inherent in all Vulcans. At that time, the mating drive outweighs all other motivations."
"And is there nothing that can disturb that cycle, Mister Spock?"
"Extreme feminine beauty is always disturbing, madam."
The pon farr was a Vulcan time of mating, and the rituals following it were shrouded under a veil of mystery and secrecy. It was considered to be a very private matter within Vulcan society, so much that only a handful of Starfleet doctors had ever handled it. Among themselves, Vulcans found it inappropriate to involve themselves with another's pon farr. (TOS: "Amok Time"; VOY: "Blood Fever")
Biology of pon farr
During pon farr, adult Vulcans undergo a neurochemical imbalance that take on a form of madness (culminating in the plak tow). A Vulcan could die within eight days if their pon farr is not satiated. (TOS: "Amok Time"; VOY: "Blood Fever") Vulcan males experienced pon farr every seven years of their adult life. (TOS: "The Cloud Minders"; Star Trek III: The Search for Spock)
The imbalance during pon farr can be transferred to others via a telepathic mating bond. It can also be transferred to other species during the same telepathic bond. (VOY: "Blood Fever") Certain microbes are also known to trigger pon farr prematurely. (ENT: "Bounty")
Vulcan females also endure pon farr. (ENT: "Fallen Hero") Normally, their hormones and endorphins rise to dangerous levels. Like males, females had to mate or otherwise receive treatment to survive. (ENT: "Bounty")
Rituals surrounding pon farr
During ancient, pre-Surak times, Vulcans typically killed to win their mates. After the Time of Awakening, the koon-ut-kal-if-fee was adopted, and many Vulcans became telepathically bonded at youth. (TOS: "Amok Time") In the early stages of mating, Vulcans generally touched fingers before touching their faces together. (Star Trek III: The Search for Spock) There were three options open to Vulcans that usually ended a pon farr: (VOY: "Blood Fever")
Notable instances of pon farr
In 2153, Sub-Commander T'Pol of Enterprise underwent pon farr after exposure to an unusual microbe. She was confined to Decon and treated by Doctor Phlox. Her premature pon farr ended when the microbes were eliminated. (ENT: "Bounty")
In the mirror universe, Lieutenant Commander T'Pol of the ISS Enterprise underwent pon farr at some point before 2155. She was assisted through this period by Commander Charles Tucker several times. (ENT: "In a Mirror, Darkly")
On stardate 3372.7, Spock had his first pon farr during a historic five-year mission which the USS Enterprise was undertaking. At the time, Captain James T. Kirk was under direct orders from Starfleet to proceed directly to Altair VI for an inauguration ceremony, with no time to stop off at Vulcan, but after coaxing Spock into telling him what was happening to him, Kirk took Spock to Vulcan anyway, knowingly risking his career. Spock invited Kirk and Doctor Leonard McCoy to attend his koon-ut-kal-if-fee ceremony.
At the ceremony, hosted by Vulcan Ambassador T'Pau, Spock's betrothed, T'Pring, claimed kal-if-fee and chose Kirk as her champion, in a move calculated to ensure that she would have her desired mate, Stonn, regardless of the outcome of the fight. During the fight, McCoy dosed Kirk with a neural paralyzer, and Spock seemingly killed Kirk, breaking his plak tow. When he returned to the Enterprise, intending to immediately surrender himself to the authorities, Spock was delighted to find that Kirk was alive and well, after all. (TOS: "Amok Time")
On stardate 8210.3, the regenerated but mindless body of Captain Spock experienced the pon farr on planet Genesis. Lieutenant Saavik was present and assisted Spock through this time. (Star Trek III: The Search for Spock)
On stardate 54238.3, Tuvok began the early stages of another pon farr. Since he was stranded aboard the USS Voyager in the Delta Quadrant, returning to Vulcan was impossible. He intended to control his pon farr with a combination of disciplined meditation and specially prepared medication. His neurotransmitters did not absorb the medication, and The Doctor was not present to prescribe an alternative. Tom Paris designed a hologram of T'Pel to handle the situation. Tuvok once again claimed to be suffering from the Tarkalean flu, although this time around, Janeway privately revealed that she was fully aware of the true circumstance in both instances. (VOY: "Body and Soul")
On stardate 50537.2, Ensign Vorik of the USS Voyager underwent his first pon farr. Due to Voyager's presence in the Delta Quadrant, he was unable to return to Vulcan and mate with his intended. He declared koon-ut-so'lik, a marriage proposal, to B'Elanna Torres, in order to gain a mate.
Vorik was injured unconsciously attempting to form a telepathic mating bond with Torres. While in sickbay, The Doctor determined that Vorik was undergoing pon farr. Vorik noted his intention to satiate his needs through meditation. He was confined to his quarters and wore a cortical monitor.
After discovering from Tuvok that Torres had also undergone pon farr, Vorik had trouble maintaining his composure. The Doctor began administering medication to control Vorik's serotonin levels. The Doctor also designed a holographic Vulcan named T'Pera to serve as Vorik's "self-healing" technique.
The Doctor declared Vorik cured of his pon farr when his cortical levels nearly stabilized following mating with T'Pera. This was a ruse, however, in order to transport to a nearby planet and attempt, once more, to mate with Torres.
After disabling communications, Vorik arrived at the planet. Once he learned that Torres intended to declare Tom Paris as her mate, Vorik declared koon-ut-kal-if-fee. Torres chose herself as champion, and the kal-if-fee was officiated by Tuvok. Vorik was knocked unconscious by Torres, and his pon farr ended. (VOY: "Blood Fever")
Sek, child of Tuvok, underwent pon farr between 2371 and 2374. His mate conceived a child, T'Meni, from this union. This news was delivered to Tuvok in 2374, on board the USS Voyager, via the Hirogen communications network. (VOY: "Hunters")
Originally, the Vulcan time of mating was to have been called "Amok-Time" and was said to affect Vulcan males "about once every 26 years." Gene Roddenberry described it that way in a memo he wrote to Gene Coon (on 5 December 1966).
Both the Star Trek: The Original Series episode "Amok Time" and the film Star Trek III: The Search for Spock state that pon farr is particular to Vulcan males. This is, therefore, at odds with ENT: "Bounty", in which pon farr is attributed to both sexes.
Pon farr is also mentioned in the Star Trek: Voyager episodes "Gravity" and "Tinker Tenor Doctor Spy". It was additionally referenced in the first draft script of the ultimately undeveloped TAS episode "Point of Extinction".
In one draft of the script for the film Star Trek, screenwriters and producers Roberto Orci and Alex Kurtzman made a reference to pon farr. "We [...] thought we should save it instead," the writers said of the reference. (Star Trek Magazine issue 149, p. 13)
The alternate reality Star Trek: Ongoing comic book "After Darkness" featured a story arc in which some Vulcans rejected the teachings of Surak due to their emotions about the destruction of their homeworld. Subsequently, they formed a group called the Sasaud (β) and turned feral. Spock briefly joined the group during his pon farr. This storyline also established that part of pon farr involved returning to Vulcan itself, with part of the current problem being the Vulcans' inability to return to their original homeworld following its destruction. Carol Marcus was able to devise a "treatment" where a transporter could be modulated to essentially recreate the conditions of beaming to Vulcan so that they could "trick" those suffering from pon farr into "believing" that they were home.
In House of Cards, the first part of the initial Star Trek: New Frontier novel series, Dr. Selar undergoes pon farr two years prior to her assignment to the Excalibur (β) and returns to Vulcan to mate with her husband, Voltak. During the course of their mating, Voltak suffers a massive heart attack and dies. This leaves Selar (β) having not completed pon farr, which she begins to suffer again two years later.