Space
The area, positive or empty, within and around a composition's forms, perceived both visually and physically.
In practice
Space is the room in and around forms, whether filled or empty. On a page it includes margins, the gaps between paragraphs and the clear area around a logo; in a room or a product, it includes physical room to move. Generous space makes content easier to read and suggests calm, while tight space feels urgent or crowded. A shop window showing one bag and a lot of empty floor uses space as part of its message.
Often confused with Counterform (Negative Space)
Space covers all the room in and around forms; negative space, or counterform, is specifically an empty area read as a shape of its own.
Try this
Double the margins and line spacing on a page of text and compare how it reads and feels.