As explained in Wikipedia.org:
"Middle class is the group of people in contemporary society who are between the working class and capitalists. This socioeconomic class includes professionals, highly skilled workers, and lower and middle management. Middle class people are also viewed as those people with a shared set of cultural values, commonly associated with professionals. In other class societies, middle class refers to people between the labouring masses and the ruling class."
This gives a pretty good idea but it's far from enough - being middle class today is very different from being middle class in the fifties or in the nineteenth century. The public connotation of the phrase has evolved, and there is a world between the lower middle class and the upper middle class. Yet, they oftentimes face the same challenges, on a different scale! How is that possible?
Our very own personal analysis (with the Middle Class Crunch touch) is coming soon folks - we're working on it. Stay tuned!