Affiliate marketing is one of the fastest growing models in digital marketing. This approach is based on the collaboration of companies with external partners (affiliates) who help attract customers in exchange for commissions, which makes the model profitable for both brands and the affiliates themselves. The theoretical foundations of affiliate marketing, its key principles and approaches, as well as the evolution of this concept in the context of constant changes in the digital space are argued. Affiliate marketing has come a long way from simple cooperation schemes in the early 2000s to integration with modern technologies such as data analytics, machine learning and artificial intelligence. An analysis of the main stages of affiliate marketing development is carried out, from the first affiliate programs to modern platforms and networks that offer complex commission models and multi-channel strategies. The advantages and disadvantages of various forms of partnerships are revealed, including the impact on the brand, traffic quality control and mechanisms for monitoring results. It is proven that affiliate marketing continues to evolve, offering increasingly effective tools for business, making it an integral part of modern marketing strategies.