All given answers here seems to be only for English.

I just want to add another language: *German*.  

German has a lot of long words (much longer as English words). If you want to typeset a German text on paper with justification you *can do it only* with hyphenations. LaTeX does a very good job with *automatic* hyphenations for the German language. It also knows the rule that in German there are only a maximum of 3 consecutive hyphens (ladders, rows above each other with hyphenations at the end of the line) allowed.

Hyphenation is only bad if it can change the meaning of the hyphenated word, for example the German verb "beinhalten" should **only** hyphenated as "be-inhalten" (contain, containing) and **not** as "bein-halten" (could be read as "Bein halten" (leg hold)).