A spacewalk is when a person in space has to put on a spacesuit, open the airlock, and step outside into the vacuum of space. There's usually no real "walking"; just a whole lot of floating and bouncing around. A spacewalk can be pretty hazardous, seeing as how the person performing the spacewalk is no longer in a controlled, breathable atmosphere and they are exposed to all sorts of radiation streaming outward from our sun. Without the protection of Earth's atmosphere, astronauts have to be very cautious when doing a spacewalk and their equipment undergoes a lot of rigorous testing to ensure that the spacewalk itself goes smoothly. Do NOT, under any circumstances, perform a spacewalk unless you are trained to do so.