Recession is typically defined as a decline in GDP for two consecutive quarters. In a typical recession, business activity goes down, consumers stop spending as much, and unemployment goes up. Of the last 4 recessions, 3 lasted six to eight months; the other one lasted 16 months.

The stock market and the real estate market often decline *before* a recession and the stock market often perks up during the middle of a recession, because the market anticipates the future recovery.

The most obvious areas of concern for the average person are: is your job secure? If you have a business, worry about a decline in business. If you have stocks, either be a long-term buy&hold investor and keep them, or if not, then at least don’t sell them at the worst possible time, which would be at the start to middle of the recession.

On the plus side, bargains can be found during a recession. It may be a good time to shop for a vacation home, a car, and to shop for stocks in the stock market, *if* your finances are secure.

Some of the other answers mention inflation. In a typical recession, inflation is kept under control because of the lack of demand; many past recessions have been deflationary or at least kept inflation to a minimum. But the ’stagflation’ of the 70’s was a notable and important exception.