Mercury-Atlas 6 (MA-6) was the third human spaceflight for the US and part of Project Mercury. Conducted by NASA on February 20, 1962, the mission was piloted by astronaut John Glenn, who performed three orbits of the Earth, making him the first US-astronaut to orbit the Earth.
The Mercury spacecraft, named Friendship 7, was carried to orbit by an Atlas LV-3B launch vehicle lifting off from Launch Complex 14 at Cape Canaveral, Florida. After four hours and 56 minutes in flight the spacecraft re-entered the Earth's atmosphere, splashed down in the Atlantic Ocean and was safely taken aboard the USS Noa ...
But there is more to the story ...
None of the Soviet Vostok missions qualified as complete spaceflights because the cosmonauts did not land with their spacecraft. Vostoks were not able to "land" so the cosmonauts had to jump out of them with parachutes. Also, Yuri Gagarin's Vostok 1 came to earth several hundred miles west of its launch point so it didn't make a complete orbit. The Soviet Union lied about both of these facts for 30 years. By then the fiction was fact.
So ... Yuri Gagarin was the first person in space (that we know of). Alan Shepard made the first official spaceflight (suborbital) and John Glenn Made the first official orbital spaceflight.