Day trading is defined as the purchase and sale of a security within a single trading day. It can occur in any marketplace but is most common in the foreign exchange (forex) and stock markets. Day traders are typically well-educated and well-funded. They use high amounts of leverage and short-term trading strategies to capitalize on small price movements in highly liquid stocks or currencies.

There is no special qualification required to become a day trader. Instead day traders are classified based on the frequency of their trading. FINRA and NYSE classify day traders based on whether he or she trades four or more times during a five-day span, provided the number of day trades is more than 6% of the customer's total trading activity during that period or the brokerage/investment firm where he or she has opened an account considers him a day trader. Day traders are subject to capital and margin maintenance requirements.
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").
Trading stocks intraday offers different opportunities than a traditional ‘buy and hold’ strategy. Speculating on stock prices via CFDs or spread betting for example, mean traders can profit from falling prices too. Margin or leverage also reduce the capital required to open a position. So you can take a position on the latest news release, product announcement or financial report – as well as technical indicators.
Day trading poses a number of hurdles. Mainly, each trading day is slightly different. Traders need a method that works in nearly all market conditions. That doesn't mean a day trader will win every day. On the contrary, even with a great method, there still may be several losing days a month. Winning every trade or every day isn't important, it is winning over the course of each week and month that matters.
The price movements of any stock are posted throughout the trading day and summarized at the end of the trading day. For example, April 2, 2019, shares of Apple Inc. (AAPL) opened at $191.09 and closed at $194.02. During the day, as indicated in the "day's range" listed to the right of the closing price, shares dropped as low as $191.05—the intraday low—and hit a peak of $194.46—the intraday high.
With low barriers to entry in the trading world, the number of people trying their hands at day trading and other strategies such as scalping has increased. Newcomers to scalping need to make sure the trading style suits their personality because it requires a disciplined approach. Traders need to make quick decisions, spot opportunities and constantly monitor the screen. Those who are impatient and feel gratified by picking small successful trades are perfect for scalping.
There are two primary divisions of professional day traders: those who work alone and/or those who work for a larger institution. Most day traders who trade for a living work for a large institution. These traders have an advantage because they have access to a direct line, a trading desk, large amounts of capital and leverage, expensive analytical software, and much more. These traders are typically looking for easy profits that can be made from arbitrage opportunities and news events, and these resources allow them to capitalize on these less risky day trades before individual traders can react.
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.
If the strategy is within your risk limit, then testing begins. Manually go through historical charts to find your entries, noting whether your stop loss or target would have been hit. Paper trade in this way for at least 50 to 100 trades, noting whether the strategy was profitable and if it meets your expectations. If it does, proceed to trading the strategy in a demo account in real time. If it's profitable over the course of two months or more in a simulated environment, proceed with day trading the strategy with real capital. If the strategy isn't profitable, start over.