What Is Middle Class?

This article at Investopedia, entitled "Losing the Middle Class", delineates the classes based on income, while mentioning that $50,000 in Arkansas is much better than $50,000 in Beverly Hills. By now everybody has heard that "the middle class is shrinking". But is that so? And if so, why? And most importantly, how can you make sure you're moving up and not down? As you can probably guess, spending less than you make and saving more of it is key. Financing an upper class (or even upper middle class) lifestyle only gets you deeper in debt and puts you one paycheck away from financial crisi.