ECNs and exchanges are usually known to traders by a three- or four-letter designators, which identify the ECN or exchange on Level II stock screens. The first of these was Instinet (or "inet"), which was founded in 1969 as a way for major institutions to bypass the increasingly cumbersome and expensive NYSE, and to allow them to trade during hours when the exchanges were closed. Early ECNs such as Instinet were very unfriendly to small investors, because they tended to give large institutions better prices than were available to the public. This resulted in a fragmented and sometimes illiquid market.
Some of these approaches require short selling stocks; the trader borrows stock from his broker and sells the borrowed stock, hoping that the price will fall and he will be able to purchase the shares at a lower price, thus keeping the difference as their profit. There are several technical problems with short sales - the broker may not have shares to lend in a specific issue, the broker can call for the return of its shares at any time, and some restrictions are imposed in America by the U.S. Securities and Exchange Commission on short-selling (see uptick rule for details). Some of these restrictions (in particular the uptick rule) don't apply to trades of stocks that are actually shares of an exchange-traded fund (ETF).
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.