Short Selling is an interesting concept, mostly revolving around speculation.
In this strategy, investors borrow shares of a stock that they believe will decline in price by a set time frame in the future (the expiration date). After borrowing the shares, investors sell them to buyers ready to purchase at the market price. Here, the trader is betting that the price will decrease further in future and they can buy the shares at a lower cost before returning and thus gaining over the margin.
However, it is risky, and should be exercised by professional traders or investors, as the price can impulse high anytime.