THE HYPHEN (-) has two main and entirely distinct functions: dividing and compounding. The former kind of hyphenation, concerning single words strictly indivisible, takes place only for typographical or other conventional reasons; the latter concerns the junction of two or more single words into a discernibly collective union. The etymology is revealing: the Late Latin hyphen derives from the Greek huphen, earlier huph'hen, literally 'under one', hence 'into one' or 'together': from hupo, under, and hen, neuter of heis, one.
The chief purposes of the typographical and otherwise conventional hyphen are these:
1. For the division of a word into syllables, as a-bout, ac-tu-a-ri-al (loosely ac-tu-ar-i-al), di-vi-sion (strict) or di-vis-ion (accepted) or div-is-ion (loose but very common). To diverge for a moment: as English has, in a sense, corrupted every long vowel, so it has also departed from the normal syllabification (British) or syllabication (American) of Greek, Latin, the Romance and most other languages. Thus, syllabication is often divided thus: sy-llab-i-ca-tion (si-lab-i-cā-shun) or sy-llab-i-cat(i)-(i)on (si-lab-i-cāsh-un). But the Medieval Latin genitive syllabicationis was divided thus: syl-la-bi-ca-ti-o-nis. The ideal is: Wherever possible, begin a syllable with a consonant.
2. When stress-the emphasis characterizing pronunciation-is added to syllabification, a word is figured thus: either (British style) or (American), where no distinction is made between the weak stress of -lab- and the strong stress of or, differentiated, (British) or (American).