When an online company runs a special promotion on swimsuits during the summer, they are taking advantage of the concept of

When an online company runs a special promotion on swimsuits during the summer, they are taking advantage of the concept of people’s urge to go for swimming to beat the summer heat and keep themselves cool. As a result, they are very likely to buy more swimsuits to go swimming. 
With a special promotion on swimsuits, people are likely to buy the company’s merchandise. This is because they can get what they want by paying a lesser amount than usual. In turn, the company is able to benefit by making more sales than its online and retail competitors.