What kinds of challenges are there facing automatic hyphenation? It seems that you could just draw word by word, breaking when the length of the line exceeds the length of the viewport (or whatever we're wrapping our text in), placing hyphens after as many characters as can fit (provided at least two characters fit and the word is at least four characters), skipping words that already contain a hyphen (there's no requirement that words have to be hyphenated).
But I note how Firefox and IE need a dictionary to be able to hyphenate with CSS's hyphens
. This seems to imply that there are further issues regarding where we can place hyphens.
What kinds of issues are these? Do any exist in the English language or do they only exist in other languages?