Organic linking

Organic linking is the development of hypertext links between web sites with or without an explicit agreement to exchange links. Organic links are more likely to appear in a context relevant to the subject of the target document, which makes them useful for search engines like Google search that rank pages according to their links.^[1] Estimates vary, but 50-80% of users clicks tend to go through organic links on the first page of a search engine's responses.

References

1. "Another step to reward high-quality sites".