A white directory is a term historically used in the SEO community to refer to a web directory or catalog that does not require a reciprocal link in exchange for adding a website to its database. This characteristic distinguishes it from so-called “black” or “gray” directories that trade links or require two-way linking.
Conceptually, white directories are considered a more ethical and less manipulative method of link building, as the link they provide is one-way and (at least in theory) is a sign of editorial approval by the directory. Since they do not require a reciprocal link, they do not contribute to the creation of “link farms” that conflict with search engine guidelines.
Although the importance of web directories as a ranking factor has decreased dramatically with the evolution of algorithms that prioritize contextual links, the concept of “white” practice remains important. It emphasizes the principle that a quality, one-way relationship that is acquired without blackmail for a reciprocal one carries greater value for building authority.