Before 1990s, due to the undeveloped network technology, there was a big time delay between the exchange rate quotations of banks, sometimes even close to 1 minute.

You see that the dollar quotation of Bank A has started to rise. You know that the quotation of Bank B is always 45 seconds later than that of Bank A. At this time, you can use the account of Bank B to make more dollars, and you can make a profit after 45 seconds.

This kind of operation needs a big market in a short time. After deducting the reaction time and operation time, the profit can be very limited, with only a thin layer, so it is vividly called "scalping".

With the development of internet technology, the time difference between bank quotations is getting smaller and smaller (now it is controlled within 4 seconds, and the interval between most bank quotations is controlled within 2 seconds). After deducting the time of reaction and operation, there is almost no profit margin, so the original "scalping" strategy is no longer used. Nowadays, scalpers usually refer to ultra-short-term trading.