Page "Spamdexing" Paragraph 31

Referrer spam takes place when a spam perpetrator or facilitator accesses a web page ( the referee ), by following a link from another web page ( the referrer ), so that the referee is given the address of the referrer by the person's Internet browser.

Some websites have a referrer log which shows which pages link to that site.

By having a robot randomly access many sites enough times, with a message or specific address given as the referrer, that message or Internet address then appears in the referrer log of those sites that have referrer logs.

Since some Web search engines base the importance of sites on the number of different sites linking to them, referrer-log spam may increase the search engine rankings of the spammer's sites.

Also, site administrators who notice the referrer log entries in their logs may follow the link back to the spammer's referrer page.