Cross-selling is a strategy where customers are offered additional products or services that complement their initial purchase, increasing average transaction value. Upselling involves offering higher-priced alternatives to the original item. Both strategies rely on matching offers with customer needs and preferences. Effective cross-sell and upsell campaigns can be implemented using recommendation engines, personalized offers, and customer journey mapping. These strategies are particularly effective when paired with technology that enables segmentation and personalization of communication channels.