Hyphenation is the necessary feature to have reflowable words in a piece of text. Just as newlines are necessary for reflowable sentences, hyphens are necessary for reflowable words. A hyphenation algorithm determines where a given word can be split up— where a hyphen, or hyphens, can be inserted. The trivial solution is anywhere within a word, but that does not bode for a nice reading experience. As such, proper hyphenation is closely related to syllabification, the process of dividing words into its syllabic parts. In my view, syllabification is a hard problem because it needs to account for locales, dialects, and stylistic choices.
Note
Example text from https://en.wikipedia.org/wiki/Syllabification
The manual example also uses a basic form of justification: The prior part of a hyphenation split may terminate the line before the max column size if the posterior part would terminate the line after the max column size; e.g. Lines 1-2, 2-3, and 5-6.
This is also applied when the word cannot be split; e.g. Lines 4-5 and 6-7
At the end of a line, a word is separated in writ-|
ing into parts, conventionally called "syllables",|
if it does not fit the line and if moving it to t-|
he next line would make the first line much short-|
er than the others. This can be a particular prob-|
lem with very long words, and with narrow columns |
in newspapers. Word processing has automated the |
process of justification, making syllabification -|
of shorter words often unnecessary. |At the end of a line, a word is separated in wri- |
ting into parts, conventionally called "sylla- |
bles", if it does not fit the line and if moving |
it to the next line would make the first line |
much shorter than the others. This can be a par- |
ticular problem with very long words, and with |
narrow columns in newspapers. Word processing has |
automated the process of justification, making sy-|
llabification of shorter words often unnecessary. |The need for hyphenation algorithms arose from the digital typesetting environment TeX. One of the first publications was Frank Liang’s PhD thesis, advised by Donald Knuth.1
Hyphenation algorithms can be split into two categories: data- or heuristic-driven. Liang’s seminal method is data-driven.