Typographic alignment
Flush left might also be used in very narrow columns, where full justification would produce too much whitespace between characters or words on some lines.
A common type of text alignment in print media is "justification", where the spaces between words and between glyphs or letters are stretched or compressed in order to align both the left and right ends of consecutive lines of text.
When using justification, it is customary to treat the last line of a paragraph separately by simply left or right aligning it, depending on the language direction.
Centered text can also be commonly found on signs, flyers, and similar documents where grabbing the attention of the reader is the main focus, or visual appearance is important and the overall amount of centered text is small.
At one time, common word-processing software adjusted only the spacing between words, which was a source of the river problem.
Modern word processing packages and professional publishing software significantly reduce the river effect by adjusting also the spacing between characters.
The technique of glyph scaling or microtypography has been implemented by Adobe InDesign and more recent versions of pdfTeX.
With older typesetting systems and WYSIWYG word processors, this was done manually: the compositor or author added hyphenation on a case-by-case basis.
The classical Western column did not rigorously justify, but came as close as feasible when the skill of the penman and the character of the manuscript permitted.
Historically, both scribal and typesetting traditions took advantage of abbreviations (sigla), ligatures, and swashes to help maintain the rhythm and colour of a justified line.
Some modern desktop publishing programs, such as Adobe InDesign, evaluate the effects of all the different possible line-break choices on the entire paragraph, to choose the one that creates the least variance from the ideal spacing while justifying the lines (so as to reduce rivers); this also gives the least uneven edge when set with a ragged margin.
