The Vulcans (also known as “Vulcanians”) are a humanoid species widely known for their logical minds and stoic culture. The Vulcan homeworld is the planet Vulcan. As a civilization, Vulcans were instrumentally responsible for the founding of the United Federation of Planets.
The Vulcans were once an extremely violent and emotional people (even by Earth standards) who waged almost constant warfare on one another. They believed in a variety of gods, such as war, peace and death. As their level of technology improved, the Vulcans eventually reached a point where their violent nature threatened species extinction.
In an effort to avoid this fate, a Vulcan named Surak developed a new philosophy thereby igniting the Time of Awakening. Surak maintained that the root cause of all the problems on Vulcan lay in the uncontrolled outpouring of the people's emotions. His followers swore to live their lives by an ethical system devised by Surak and based purely on logical principles. Emotions were to be controlled and repressed.
Eventually, however, those who opposed logic left Vulcan and founded colonies elsewhere - most notably on the planet Romulus, where they founded what eventually became the Romulan Star Empire.
The official first contact between Vulcans and Humans came on April 5, 2063 when a Vulcan survey ship detected the warp flight of Zefram Cochrane's Phoenix. The Vulcans met with Cochrane at his launch site on the day following the flight.
As of the 23rd century, Vulcan had never been conquered in its collective memory. That memory goes so far back that Vulcans can't conceive of a conqueror.
Today, Vulcan remains one of the principal Federation members, and is deeply involved in all levels of that society. Their tradition of exploration has continued.
Genetically, Vulcans and Humans are similar enough that they can produce offspring without any problems.
Externally, Vulcans are generally similar to Humans, the chief exceptions being the Vulcans' notably arched and upswept eyebrows and distinguished external ear structure, the top of which tapers into a clearly defined point.
Most Vulcans have straight, glossy dark brown or, more commonly, black hair and pale skin with a very subtle greenish tinge, much as the skin of Humans of European descent has a very subtle reddish/pinkish tinge.
In contrast to their external similarities, Vulcan internal anatomy differs radically from that of Humans. For instance, their heart is where a Human's liver would normally be and beats several hundred times per minute. They also have no appendix.
Vulcan blood is copper-based and is copper- or rust-colored when deoxygenated in the veins and green when oxygenated in the arteries. Bruises and dermal abrasions therefore take on a green color.
Vulcan body chemistry uses little, if any, sodium chloride compared to that of humans. Vulcans possess a highly efficient respiratory system to extract the oxygen they need from Vulcan's thin atmosphere. They are most comfortable in high temperatures, which is natural given the hot, arid climate of their homeworld.
Vulcan hearing is very sensitive. Having evolved on a planet which is mostly desert, Vulcans have developed ways of surviving in desert conditions. For example, they can survive for several days without water and have inner eyelids which protect their eyes. Vulcans have a superior metabolism to Humans. Caffeine and sapotoxins have little effect on them. They are also capable of surviving for long durations without food or sleep. Under stress, Vulcans can do without sleep for weeks.