Cross selling is the term which is often used in the context of banking; under it the employees of the bank cross sell various products apart from normal banking products to their customers. Those products may be insurance, mutual fund, gold coins and so on. In simple words cross selling is a form of marketing where the potential customers and existing customers are same. The biggest advantage of it is that one does not have to search for new customers for products rather one can sell it to its existing customers who are more likely to buy the product as compared to new customers.
It can be used anywhere apart from financial industry, however too much of it can lead to your existing customer getting irritated which in turn will result in company losing that customer also. Hence the company should take care that they offer only those products which are of their interest and can genuinely benefit their existing consumer.