The Single-entry, Short-stay Visa allows the holder to visit one or more of the Schengen countries for up to 90 days within a six-month period. However, the traveller is only allowed to enter the Schengen zone once. If the traveller leaves the Schengen zone, their visa expires and they will no longer be allowed to return, and this applies even if they have not stayed 90 days in the Schengen zone. A Multiple-entry, Short-stay Visa allows as many journeys into and out of the Schengen zone as the holder requires, but still limits the overall visit to 90 days within a six-month period.