They are the services that are offered in addition to any business's core service and assist the customer in using that service. Complementary products and services are products and services which have indirect impact on the utility a buyer receives from an offering. What is important is the total solution buyers expect when they choose a product or service. For example- babysitting help and parking facilities are two complementary services that are provided in movie theaters.
For an organization specializing in pet photography, the market is one that pampers the customer’s pets. So logical complementary products and services may include pet grooming, or clothing for pets. Usually, the complementary good does not have much value when it is consumed alone but in combination with another good or service, it adds on to the overall value of the offering.