Let me see what I can clarify...hmmm..... Chinese...is all written the same, but can be read differently in a different dialect. pinyin is the romanization for chinese mandarin only and it is based on phonetic writing of the mandarin speech. another phonetic writing is jyutping and this is a romanization of the cantonese speech. there are other types of phonetic writings as well like for shanghainese and taiwanese but I don't know the name for it. every chinese character can be read in their own dialect but not really spoken the same way. for example cantonese cannot be fully written out because it is full of slangs. if a cantonese speaker writes in cantonese chinese it would look a little funny to a mandarin speaker. Chinese mandarin is the standard language for China. But there are still some people that don't know mandarin. or can't speak it well. sorry for not typing neatly...I feel tired and lazy right >.<;

Oh,Niney Chan's answer is detailed,that's right~=)

u can learn chinese in cri (china radio international ),there is aula de chino in the station

Yes it's true,and almost Chinese can understand mandarin pinyin(maybe some Cantonese can't...I guess). But Chinese dialects is difficult to understand..I even can't understand some of them.= =