Suggestions to customers for products they may be interested in based on products they’ve already bought or viewed online. For example, if a customer bought the same tank top in 3 colors, there’s a good chance they’ll like the same tank in a new color. Personalized product recommendations, which mathematical calculations called algorithms determine on the back end, are a key feature of websites for cross-selling and upselling.

Combining Email Marketing with Other Types of Marketing
Whether you choose to do your marketing online or offline, one thing does not change. This is the concept that no single marketing strategy will be as effective as a combination of two or more marketing strategies.