Day trading is the practice of buying stock on the stock market, holding it for an extremely short period of time (typically less than a day, hence the name), and then selling it, hopefully for a profit. It is possible to make (or lose) large amounts of money very quickly by day trading. Day trading is regarded as an extremely risky investment strategy, as the stocks used for this procedure are typically extremely volatile and subject to great price fluctuations.

Successful day trading as a primary source of income requires a large amount of starting capital to invest, as day traders typically attempt to capitalize on small fluctuations in stock prices.

Many day traders purchase software packages that allow them to trade from home on a personal computer. Others work for investment houses, and still others join together in associations of private day traders who pool resources to rent an office space where they can all come every day to trade, socialize, and share stock tips.