The systems by which stocks are traded have also evolved, the second half of the twentieth century having seen the advent of electronic communication networks (ECNs). These are essentially large proprietary computer networks on which brokers can list a certain amount of securities to sell at a certain price (the asking price or "ask") or offer to buy a certain amount of securities at a certain price (the "bid").
Retail investors are prone to psychological biases that make day trading difficult. They tend to sell winners too early and hold losers too long, what some call “picking the flowers and watering the weeds.” That’s easy to do when you get a shot of adrenaline for closing out a profitable trade. Investors engage in myopic loss aversion, which renders them too afraid to buy when a stock declines because they fear it might fall further.
In addition to knowledge of basic trading procedures, day traders need to keep up on the latest stock market news and events that affect stocks—the Fed's interest rate plans, the economic outlook, etc. So do your homework. Make a wish list of stocks you'd like to trade and keep yourself informed about the selected companies and general markets. Scan business news and visit reliable financial websites.