The people in China speak mandarin but use simplified Chinese for writing. Hong Kong and Taiwan use traditional Chinese. The Chinese are starting to take over Hong Kong so I would suggest you learn mandarin because the majority of the people in China, Taiwan and Hong Kong speak Chinese. As for writing if you are going to China then I would suggest learning simplified Chinese but if you want to go to Taiwan or Hong Kong learn Traditional Chinese. I live in Taiwan now and the teachers don't like it if you use simplified Chinese at school but I don't think the people in China care. It all really just depends on where you want to go.
“The table below solves the riddle: In mainland China and Singapore, Mandarin is the spoken language and people resort to Simplified Chinese when they write. In Hong Kong, Cantonese is the predominant dialect while people write in Traditional Chinese.”
