WHO
  WHAT
  WHERE
  HOW
  WHY
  WHEN
  COST

What?

A space settlement is a home in orbit.

• Rather than live on the outside of a planet, settlers will live inside of large spacecraft. Free-space settlement designs range from 100 meters to a few kilometers across. A few designs are much larger.
• Settlements must be air tight to hold a breathable atmosphere, and may rotate to provide psuedo-gravity. Thus, people stand on the inside of the hull.
• Settlements close to Earth and near the equator are protected from most space radiation by the Earth itself and the Earth's magnetic field. Further from Earth enormous amounts of matter, probably lunar regolith and asteroidal materials, must cover the settlements to protect inhabitants from radiation.
• Each settlement must be an independent biosphere. All oxygen, water, wastes, and other materials must be recycled endlessly.

For more information:
What is an Orbital Space Colony?
Pictures of space settlements
Pictures of Kalpana One
Lewis One space settlement design