The term spamdexing is a portmanteau of the words “spam” and “indexing”. It’s used by SEO professionals to refer to the manipulation of the indexing function on search engines by creators of spam. The aim is to manipulate SERP rankings and drive or generate traffic to certain websites – this might be used to provide information for a later scam too.
It’s a catch-all term for several practices that are considered to be shady and underhand or unethical. As Google updates its algorithms, it becomes harder for webmasters and marketers to use spamdexing techniques, as they become known to Google and, when identified, actually serve to demote a webpage’s rank rather than the intended promotion.