The goal of swing trading is to capture a chunk of a potential price move. While some traders seek out volatile stocks with lots of movement, others may prefer more sedate stocks. In either case, swing trading is the process of identifying where an asset's price is likely to move next, entering a position, and then capturing a chunk of the profit from that move.
This is usually reserved for traders working for larger institutions or those who manage large amounts of money. The dealing desk provides these traders with instantaneous order executions, which are particularly important when sharp price movements occur. For example, when an acquisition is announced, day traders looking at merger arbitrage can place their orders before the rest of the market is able to take advantage of the price differential.
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.
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.

Successful traders have to move fast, but they don't have to think fast. Why? Because they've developed a trading strategy in advance, along with the discipline to stick to that strategy. It is important to follow your formula closely rather than try to chase profits. Don't let your emotions get the best of you and abandon your strategy. There's a mantra among day traders: "Plan your trade and trade your plan."