The offering of complementary or related products to a customer is known as cross-selling. As a form of marketing, it is highly effective. One example of cross-selling is to offer various types of products or investments to investors in the financial services industry. Similarly, selling tax preparation services to clients who are planning their retirement is another instance of cross-selling. A bank sales team may try to cross-sell a savings product such as a Certificate of Deposit (CD) or a personal line of credit to a client who has a mortgage.