White space is a necessity in design composition. Generally design is made up of positive space and negative space. Balance of the two is good. Negative space is sometimes known as non-printable area while the positive space (Design image) is also known as printable area.
In the diagram above the black shape is the image area (positive space) while the white area is the negative space (non-printable area).
Space helps to separate and connect elements of design. By this we create rhythm, direction and motion. Negative space if applied well can be used to achieve a professional design work.
Just like human will need water when thirsty, food when hungry and sex when in the mood, so does every good design need space to breath.