What is a Link Farm?
A link farm is a group of websites or pages that link to each other, or list links in bulk, mainly to inflate the number of links pointing to a site.
Why it matters
Link farms rely on volume. Instead of earning a link from a site with its own audience, the operator gets many links from pages that exist only to hold them. Google's spam policies describe link spam as creating links primarily to manipulate rankings, and link farms are a clear example. Links from them are unlikely to help, and associating a site with them adds risk, even when the owner did not build them.
How to recognize a link farm
A link farm is recognizable by what it lacks. There is no real audience or organic traffic, no editorial standard, no coherent topic, and the links point to unrelated sites. Pages often list links with little or no surrounding content, and anyone can add a link. A site that fails those checks should be avoided as a source of links, whatever its metrics say.
Link farm patterns
Directory style farms
Pages or sites that accept links from anyone and list them, with little or no editorial review.
Automatically generated networks
Large sets of pages created by software to hold links, usually with thin or copied content.
Link exchange rings
Groups of sites that link to each other in a closed pattern so that each appears to receive links from others.
Example
A site is listed on a page that holds hundreds of links to businesses in unrelated industries. The page has no readers, no meaningful text and no reason to exist other than to list links. A link there adds nothing for users and looks like link spam to a search engine.
Link farms and Orbink
Orbink lists sites that accept sponsored content and shows metrics such as organic traffic, DR and the niches a site accepts on each listing, which gives you a starting point to check whether a site has an audience.
Read the Unnatural Links GuideSources
Frequently Asked Questions
Links created primarily to manipulate rankings are link spam under Google's spam policies, and link farms are built for that purpose. Google can ignore such links and can apply a manual action.
Google says it works to make sure actions on third party sites do not negatively affect a website, and most such links are simply ignored. A site that built or bought them itself carries more risk, and Google may act on a pattern of manipulation.
A PBN is a controlled set of sites run by one operator. A link farm is usually a more open collection of pages that exchange or list links in bulk. Both exist to pass links, not to serve readers.
Most of the time, nothing: Google can ignore these links. If you have a considerable number and a manual action is a concern, follow Google's guidance on removal and the disavow tool.