Phoenix in spaceflight
Spaceflight or space travel referred to transportation or travel through space on a vehicle called a spacecraft. Some more advanced pre-warp cultures possessed limited spaceflight capabilities, although they were mostly bound to their own solar system because their space vessels were sublight, meaning they weren't as fast as the speed of light. Spaceflight was a vital component of space exploration.
Warp-capable civilizations, such as the Federation or the Klingon Empire, were capable of interstellar spaceflight, and in fact both superpowers were interstellar nations.
While underground on Minara II, Doctor Leonard McCoy made the comment that living so far underground wasn't natural. Captain James Kirk then stated "And space travel is?" (TOS: "The Empath")
According to certain reports, the Sarpeidon natives did not possess spaceflight capabilities, which is why the crew of the USS Enterprise was surprised to find that their homeworld had been evacuated. (TOS: "All Our Yesterdays")
In 2285, while Spock's katra inhabited his body, giving him the appearance of madness, Doctor McCoy was attempting to charter a spaceflight to the Genesis Planet at a bar in San Francisco. When a Federation Security agent overheard his conversation, he offered to give the doctor a ride home. Dr. McCoy did not see the logic in such an offer, since he was trying to charter a spaceflight. (Star Trek III: The Search for Spock)
The two major planets of the Beta Renner system, Antica and Selay, contained the major lifeforms Anticans and Selay who had become deadly enemies since achieving spaceflight. (TNG: "Lonely Among Us")
In 2372, Captain Kathryn Janeway noted that, an unspecified number of years beforehand, Starfleet used a technology to assist deep space travel by keeping the body in stasis and providing an artificial environment, or mental landscape, to keep the mind active and alert. (VOY: "The Thaw")