Follow These site:- http://en.wikipedia.org/wiki/Mandarin_Chinese

Mandarin is one of the 7 geographical dialects in China,which is is representative,Mandarin speakers is widely distributed over northern China,about 1 billion people.the "普通话（putonghua）" consist of the most common pronunciation and word in inner dialect of Mandarin .

This word has some connections with the history in China . Mandarin , first used in the Dynasty Qing by the British to name the chinese officers in the court. We refer to "Mandarin"as "清朝官员"in the first place. And the language they were using was also seen as madarin:"官话"--"北京话"--"普通话". And that also explains why Mandarin was taken as the official language in China .

Mandarin Chinese (also putonghua, goyu, huayu) is official language of Mainland China, Taiwan, and Singapore. The word mandarin originally meant something like "official.. like official in imperial China", nowadays when someone says Mandarin Chinese he refers to northern dialects, on which Standard Chinese language is based. Hmm.. I think that the word mandarin also means a kind of fruit that looks similar to orange but usually smaller in size... Though it has nothing to do with Chinese language.

普通话