Affiliate links

What are they, and why are they used?

An affiliate link is a way for content creators to recommend products they use and like, in exchange for which they may receive a small commission from the person or company selling whatever the link leads to. The person who follows the link and buys the product doesn't pay more for it because they followed an affiliate link.

Affiliate links are one way to monetize online offerings so that content creators can earn some revenue without having to  charge the viewer/listener/reader for their content.