Condensation happens on cold surfaces and in places where there is little movement of air. It often appears as a dark patch in corners near the skirting and on the ceiling.
Areas with poor ventilation can be prone to condensation. This could be behind furniture; particularly wardrobes, beds drawers and even clothing if they have been placed against an outside wall. Condensation can happen in any room but it is most likely to occur in your bathroom, bedrooms and hallway as they are generally cooler.
Moisture in the form of condensation is most commonly found in bathrooms and is easily seen on tiles. To prevent mould, open the window after bathing or showering, wipe the tiles down and close the door.