I'd add to this a few terms that I've encountered: Unicode, locales, UTF-8, UTF-16, wchar_t, Latin-1, Shift-JIS, ISO-8859, BOM, encoding, PO file, gettext, code pages, LC_ALL...
It takes an awful lot of time and intellectual bandwidth to merely understand the problem domain and existing technologies, let alone figure out the best way to apply that understanding to your situation and write working code. Compounding the problem, many real products rely heavily on third-party components, libraries, and frameworks, and often they are buggy when it comes to dealing with international text.
So I'd say, for most startups: Localization is a rich man's problem. Focus on your own language first. Once you have an MVP and have either gotten VC funding, or become profitable from revenue, then you can simply hire someone who understands localization to implement support for different languages.
I've discussed this before .