FFA: FFA stands for “free for all,” referring to pages that allow any user to submit links to them. An FFA page does not charge for this service and does not require the user to backlink to the FFA site.
FFA links are sometimes used as rudimentary search engine optimization, since the number of links pointing to a site have an effect on its ranking in search results.
Good SEO techniques avoid these sites because the algorithms determining search engine ratings take into consideration not only how many links point to a site, but the quality of the sites hosting those links. Automated programs are often used to fill FFA pages with links pointing to low-quality sites, meaning that search engines don’t judge them as having enough authority to determine the relevancy of a page. Some view this method of link building as an unethical, or “black hat” SEO technique. In some cases, having too many FFA links can cause search engines to flag a website as spam and implement penalties on its ranking.
Since submitting links to FFA pages is at best ineffective and may lead to a website being flagged as spam, it is best to avoid them altogether. Google has directly warned web developers against FFA techniques, as well as other link-building scams.