UnicodeとUTF-8の違いは？ - おつあり
http://d.hatena.ne.jp/tyru/20091129/difference_between_unicode_and_utf8

(via mi-ka-n)

When you talk about “text,” you’re probably thinking of “characters and symbols on my computer screen.” But computers don’t deal in characters and symbols; they deal in bits and bytes. Every piece of text you’ve ever seen on a computer screen is actually stored in a particular character encoding. Very roughly speaking, the character encoding provides a mapping between the stuff you see on your screen and the stuff your computer actually stores in memory and on disk. There are many different character encodings, some optimized for particular languages like Russian or Chinese or English, and others that can be used for multiple languages. In reality, it’s more complicated than that. Many characters are common to multiple encodings, but each encoding may use a different sequence of bytes to actually store those characters in memory or on disk. So you can think of the character encoding as a kind of decryption key.

Everything you thought you knew about strings is wrong.

also about UTF-32, UTF-16, UTF-8

Unicode is a standard, UTF-8/16/32 are encodings.

These days its pretty standard to require support for multiple languages and special characters on your website. But it’s still terribly easy to trip up and make mistakes, usually indicated by weird characters popping up across your web content. Here’s a few tips on how to sort out your character encoding.

These days its pretty standard to require support for multiple languages and special characters on your website. But it’s still terribly easy to trip up and make mistakes, usually indicated by weird characters popping up across your web content. Here’s a few tips on how to sort out your character encoding.