NASA astronaut Edward White became the first American to perform a spacewalk on June 3, 1965. The walk took place during the Gemini 4 mission and lasted for about 23 minutes. In that time, White drifted weightlessly in Earth's orbit from high above the Pacific Ocean near Hawaii, to above the Gulf of Mexico, tethered by one cord.
A gun expelling oxygen was used propel White through space, until it ran out of fuel and he resorted to pulling on his tethered cord in order to return to the capsule. Since that time, astronauts have performed hundreds of spacewalks to make repairs, upgrade and checkup on spacecraft.
It's hard to imagine what it must feel like to step out of a craft and into nothingness, but images are the closest most of us will ever come to the experience.
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Additional reporting by NASA.