Following the 1987 stock market crash, the SEC adopted "Order Handling Rules" which required market makers to publish their best bid and ask on the NASDAQ. Another reform made was the "Small-order execution system", or "SOES", which required market makers to buy or sell, immediately, small orders (up to 1000 shares) at the market maker's listed bid or ask. The design of the system gave rise to arbitrage by a small group of traders known as the "SOES bandits", who made sizable profits buying and selling small orders to market makers by anticipating price moves before they were reflected in the published inside bid/ask prices. The SOES system ultimately led to trading facilitated by software instead of market makers via ECNs.
Spreads are bonuses as well as costs - Stock Markets operate on a bid and ask based system. The numerical difference between the bid and ask prices is referred to as the spread between them. The ask prices are immediate execution (market) prices for quick buyers (ask takers); bid prices for quick sellers (bid takers). If a trade is executed at market prices, closing that trade immediately without queuing would not get you back the amount paid because of the bid/ask difference. The spread can be viewed as trading bonuses or costs according to different parties and different strategies. On one hand, traders who do NOT wish to queue their order, instead paying the market price, pay the spreads (costs). On the other hand, traders who wish to queue and wait for execution receive the spreads (bonuses). Some day trading strategies attempt to capture the spread as additional, or even the only, profits for successful trades.
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.