Stock markets are an organised mechanism through which a business could offer shares and other securities for sale for the investor to buy. To list on the stock market means to find a specific stock exchange to trade on. However, stock markets can also be composed of Over the Counter trading, as well as Electronic Communication channels thus having a breadth of avenues through which to trade.
For example…
The U.S. Stock market is comprised of several large stock exchanges where businesses list their stock like NYSE and NASDAQ. It also consists of the Over the Counter Market, like otcmarkets.com where all U.S government and municipal bonds are traded, without trading floors like the NYSE.