Simple definition of recommendations:
Smart cross-sections of the complete assortment, to make it easier for visitors to find the desired products and at the same time increase conversion and order value.
Recommendations can be deployed in various positions in your webshop. For example, featured products on your home or category pages or in emails. Or related products on a product detail page, your shopping cart or in an email. Read Which types of recommendations are there? to discover the possibilities.
Recommendations can really boost your average order values. Around 35% of Amazon's turnover, for one, comes from product recommendations.