As a general guide, the ideal word space represents the width of the lower case 'e' in the type face being used. With the taste for narrow spacing still growing, some authorities suggest that the ideal word space is the width of the lower case 'i' in the type being used. For this width to be practical however, there is a need to reduce the set-width of the font being used. In display composition, correct spacing between groups can affect the appearance and readability of type matter. In this situation, the wishes of the person designing the job will govern the amount of space to be used.
Variety is a very important principle in spacing, just as much as type face selection or type sizes.
Uniform space between groups in display setting leads to monotony and as a consequence, an uninteresting appearance. In spite of the necessity for variety in spacing between groups, it must be achieved only after due consideration of how varying amounts of space are to be placed. Space is used to separate one thought or section of copy from another, therefore the amount of space should be varied according to how isolated one thought is from another. The readability of a piece of printed matter can be assisted or marred by the placing of the space between lines or groups. Display Display setting is the highest form of punctuation, this is where spacing of groups is applied.