Not every stock is traded on the New York Stock Exchange or NASDAQ.
Historically printed on pink paper, these smaller stocks are called pink sheet stocks or Over the Counter Stocks. Another phrase you'll hear is penny stocks.
These smaller companies and certain foreign companies are traded on this exchange. The stocks are usually highly volatile startups that are either the next big thing or scams designed to part you from your money.
Be careful because these stocks are very volatile.
They do not have to undergo the same vetting process as regular SEC registered stocks, although some do register with the SEC.
SEC page with Pink Sheet Information
Homepage for OTC Markets