Justification is the alignment of text along a margin. To produce good-looking justification, the word processor and printer must be capable of microspacing; that is, they must be able to separate letters by less than a full space. In addition, justified text always looks better when a proportional font is used.
Vertical justification refers to adjusting the vertical space between lines so that columns and pages have an even bottom margin. One vertical justification technique, called feathering, inserts an even amount of space between each line so that the page or column has a specified vertical length.