How would you thank your user? How would you know what language he is using? And finally, how would you distinguish one language variant from the other (US english from GB english)? For all that cases you need locale tag. It is designed to store every information important to proper localization. We have many standards out there, but only one can be considered true standard.
Back to 2005 I had no idea what is character encoding, why I see � in text files or what is the difference between Unicode and UTF-8. It looked so complicated, that I felt like a blind man every time I needed to deal with this. In this article you will learn all nuances of encodings, why UTF-8 had become standard and how they call unreadable characters in Japan.
Almost one year ago, Unicode 7.0.0 was released. At that time it added support for almost 3000 new characters. On 2015-06-17, exactly one year and one day later Unicode 8.0.0 was announced. What does it change?