A share of stock is one of a finite number of equal portions in the capital of a company, entitling the owner to a proportion of distributed, non-reinvested profits known as dividends, and to a portion of the value of the company in case of liquidation.
But these days, companies don't really pay dividends. I think this trend started during the tech bubble, when people still bought stocks even when there wasn't any revenue, and therefore there weren't any dividends...so other companies said "wait, what? We don't have to pay dividends?"
So the only value to a stock is if the company is liquidated (or sold). If the company is liquidated in the usual sense (bankruptcy) then the stock is worthless.
It seems to me that the only reason to buy stock (in most companies, where you don't have any voting rights to determine the direction of the company) is to speculate that the value will go ever upward. This sounds a lot like the foundation of sand underneath the financial crisis, that everything would be fine as long as house prices went up forever. And if they didn't? Well, we didn't even contemplate what would happen.
I am certainly no economist, and the more I read the less I understand. But it's another sign of the way our whole economy has divorced itself from producing anything, and is more about moving money back and forth and making money by taking a cut of every transaction. That can't bode well.