Day trading was once an activity that was exclusive to financial firms and professional speculators. Many day traders are bank or investment firm employees working as specialists in equity investment and fund management. Day trading gained popularity after the deregulation of commissions in the United States in 1975, the advent of electronic trading platforms in the 1990s, and with the stock price volatility during the dot-com bubble.[2]
As with any other style of trading, many different methods of scalping exist. The most well-known scalping technique is using the market's time and sales to determine when and where to make trades. Scalping using the time and sales is sometimes referred to as tape reading because the time and sales used to be displayed on the old-fashioned ticker tape, known as the tape.

This combination of factors has made day trading in stocks and stock derivatives (such as ETFs) possible. The low commission rates allow an individual or small firm to make a large number of trades during a single day. The liquidity and small spreads provided by ECNs allow an individual to make near-instantaneous trades and to get favorable pricing.
There are a variety of methodologies to capitalize on market swings. Some traders prefer to trade after the market has confirmed a change of direction and trade with the developing momentum. Others may choose to enter the market on the long side after the market has dropped to the lower band of its price channel—in other words, buying short-term weakness and selling short-term strength. Both approaches can be profitable if implemented with skill and discipline over time.
Spot foreign exchange (exchanges of foreign currencies) brokers - They do not charge any commissions because they make profits from the bid/ask spread quotes. On July 10, 2006, the exchange rate between Euro and United States dollar is 1.2733 at 15:45. The internal (inter-bank dealers) bid/ask price is 1.2732-5/1.2733-5. However the foreign exchange brokers or middlemen will not offer the same competitive prices to their clients. Instead they provide their own version of bid and ask quotes, say 1.2731/1.2734, of which their commissions are already "hidden" in it. More competitive brokers do not charge more than 2 pips spread on a currency where the interbank market has a 1 pip spread, and some offer better than this by quoting prices in fractional pips.
The intraday trading strategy to be used also depends upon the traders’ personal trading styles, along with being dependent on the market conditions. Some traders are very active and do many trades a day, with large position sizes, catching even the small price movements; while there are others who trade only on specific news events or only on tendencies that they have well researched.
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.