Referrer spam (also known as log spam or referrer bombing) is a kind of spamdexing (spamming aimed at search engines). The technique involves making repeated web site requests using a fake referrer url that points to the site the spammer wishes to advertise. Sites that publicize their access logs, including referrer statistics, will then end up linking to the spammer's site, which will in turn be indexed by the search engines as they crawl the access logs.
This benefits the spammer because of the free link, and also gives the spammer's site improved search engine ranking due to link-counting algorithms that search engines use.
Referrer spamming consumes server resources which are paid for by the website owner or ISP. It slows down access to the site for normal surfers. It uses disk space. It clogs weblogs with bogus information. It subverts the ranking mechanisms used by search engines. Spammers are nothing more than leeches sucking the lifeblood out of the web.
It should also include those who post only to expose their spammy signature links. The sig links here at Daniweb cannot be seen by anyone other than Daniweb members, so most are just wasting their time.
This description applies to the OP who has asked 6 different questions in separate threads and obviously has no interest in the answer(s).