A satellite site is a web resource that is created to complement, support and promote a main, target website (the so-called “money site”). Its concept is to function as a strategic support, providing additional traffic, broader keyword coverage and most importantly – passing link weight (link juice) to the main resource, thereby increasing its authority and ranking in search engines.
Architecturally, satellite sites can be built around narrowly specialized niches or cover marginal keywords that are not covered by the main site. They act as relevancy signals to the target site. Depending on the practice, satellite sites can range from completely legitimate, high-quality resources (when used for brand expansion) to a form of manipulation (when used to create an unnatural PBN structure).
The key difference between a satellite and a PBN is the question of quality and intentions. While a well-built satellite site can provide real value to users, sites that are part of artificial networks are often low-quality and fall within the scope of search engine punitive algorithms.