In typography, the breaking of a word into syllables and inserting hyphens, manually or automatically, so that word spaces remain consistent—within prescribed limits—for proper justification.
There are several basic rules for hyphenation:
1. There must be at least two characters on both sides of the hyphen.
2. Numerals should not be hyphenated except, in an emergency, at a comma point.
3. It is not good practice to hyphenate in a headline.
4. A one-syllable word should never be hyphenated, though some systems will certainly try.
5. A word should be divided on a double consonant, unless the word root ends with a double consonant (e.g., miss-ing, not mis-sing).
6. More than three hyphens should not be used in a row. Too many hyphens in a row (or too many hyphens in a text block) is referred to as pig bristles.
An incorrect word division is called a bad break. For maximum legibility, hyphenation should be used as little as possible.
A discretionary hyphen is inserted in a word during input to give the system a specific point to hyphenate, and that point will take precedence over any logic-generated point. Often, a DH at the beginning of a word tells the system not to hyphenate the word at all.
Logic hyphenation refers to a system where the computer is programmed with certain logical rules for hyphenating words at the ends of lines. However, no program is infallible. Hence, the need for an "exception dictionary," a collection of the program's incorrectly hyphenated words held in the computer's memory. With luck, the system will search the exception dictionary before consulting the logic program.