A detached house is a property which doesn't share an inside wall with any other house or building. So essentially, it only has outside walls and doesn't touch any other properties. Think, Buckingham Palace not 10 Downing Street. Detached homes are typically popular with families and often include a garage, a garden or other outdoor space.
Detached houses have their positive aspects. One key advantage is that the owners or renters have a private space and in many cases the option of adding extensions like a conservatory or a larger garage.