Shanghainese is the local dialect spoken by the people who live in Shanghai and the area surrounding it. It belongs in a larger group of dialects, Jiangsunese, after the Jiangsu province. Jiangsu is a big place, just like most other chunks of Chinese dialects, Jiangsunese is quite diverse, each major city has their own dialect. Shanghainese is the major dialect of the region, however, it is completely different from Nanjingnese, the other major dialect of the province. I suspect that Shanghainese developed from either Nanjingnese (the Nanjing dialect) or Suzhounese (Suzhou), for Shanghai was little more than a fishing village a few centuries back, and Nanjing has been around for eons, Suzhou even longer. My rudimentary knowledge of Shanghainese leaves me no chance of understanding any of the other Jiangsu dialects.

Shanghainese is notoriously difficult to learn, even more so than Cantonese, because a large part of their characters are only known through the word of mouth and never written down. Almost all Chinese dialects have their little special terms, however, Shanghainese has far too many. It is spoken in a rolling brogue; Shanghainese is like the Irish dialect of Britain. Odd accents in strange places. I don't know a single foreigner who speaks good Shanghainese. Save Harrison Ford in the intro to the movie "Temple of Doom", but he had a bad accent. Narf.

As one goes west from Shanghai, other dialects in the family can be found, from Wuxi to Nanjing, all unique. The seemingly oral tradition of the Jiangsu dialects is interesting, however, it is probably because I am not a native speaker. There are many tones (or consonants) in this dialect, perhaps as much as Cantonese, however, the lack of written material prevents me from doing research.

An interesting sidenote is that many famous Chinese poets came from this region. Poems, if read in different dialects, sound quite horrible, but when they are dictated in the poet's native dialect it makes much more sense. This testifies to the ongoing evolution of the Chinese language, these dialects have been developing for centuries.