Link content spam

When a link exists on a page A to page B only to affect the hub component of page A or the authority component of page B, that is an example of content spam on page A. Page B is not spamming at all. Page A should receive a spam penalty. Without further evidence, page B should not receive a penalty.

Link meta spam

When the anchor text or title text of a link either mis-describes the link target, or describes the link target using incoherent language, that is an example of link meta spam.

Here are some practical examples of link spam:

an SEO house stuffs the noframes content of a client's framed home page with spam, including a link to the SEO's web site to attempt to influence the authority factor of their site. Result: The client receives a spam penalty for all the spam, including the link. The SEO's web site receives no penalty for the link, in the absence of any further evidence.

A guerrilla web marketer places a competitor's Web site in a link farm, hoping it receives a spam penalty. Result: the competitor Web site receives no penalty since, because it is not an active participant in the link farm (it does not link to other sites in the farm), there is no evidence of spam abuse. It also receives no credit for the links it receives, because they come from a link farm.

Here is a general rule of thumb to determine whether link spam has taken place - if the link is not designed to be followed by humans, or the page it is on is not designed to be read by humans, then it is spam.

Redirects

There are many means of redirecting from one Web page to another, none of which were invented for spamming, but all of which can be subverted for spamming. Examples of redirection methods are HTTP 300 series redirect response codes, HTTP 400 series error vectors, META REFRESH tags and JavaScript redirects. Where a redirect is used to move a human quickly from a page that has been designed for a search engine to see to a page designed for a human to see, then the whole page designed for the search engine to see is spam. Everything on it is an example of either content spam or meta spam.

However, since redirection wasn't invented to facilitate spamming, the existence of a redirect should not of itself indicate spam. A search engine robot seeing a HTTP series response or short META refresh should follow the redirect to the target, without indexing the source.

Here are some practical examples of redirection:

An SEO produces a page of gobbledegook designed only for a search engine to see, tuned for a particular keyword to match the keyword density the SEO believes the search engine's algorithms currently use. The SEO places this content after a screenful of paragraph breaks so human visitors to the page will not see it without scrolling. The SEO then uses a JavaScript include file to redirect to another page designed for humans to see. Result: This is spam. Humans that visit the page with JavaScript disabled get gobbledegook. The site's brand is damaged and the human does not become a customer. If the human chooses to report the spam to the search engine, the site on which the page sits receives a spam penalty.

A Webmaster restructures her Web site and inserts Redirect lines into the server configuration file to ensure visitors that follow links to the old pages automatically end up at the correct new pages. The search engine robot therefore receives a HTTP 300 series response when it requests a particular page. Result: the search engine robot should follow the redirect and treat the target page as any other page on the Web. This is not spam.

Agent-Based Delivery and Agent-Based Spam

Agent-Based Delivery was invented at almost the same time as the Web itself. It uses fields of the HTTP request header, in particular the User-Agent field, in order to deliver the content according to features such as the platform and language of the visitor. In other words, different content is delivered from the same URL according to the HTTP request.

Agent-Based Delivery can be subverted to deliver spam to search engines. However, Agent-Based Delivery also has a purpose that does not depend on the existence of search engines. Therefore, the use of Agent-Based Delivery does not necessarily indicate an intention to spam a search engine.

We will now briefly discuss the use of Agent-Based Delivery and some of the implications.

Let's suppose that a webmaster uses Agent-Based Delivery to deliver one version of a Web site to Mozilla browsers, and another version of the same web site to non-Mozilla browsers. A search engine, as a non-Mozilla browser, sees a different version of a Web site than a human visitor that uses a Mozilla browser. Is this spam? The answer is either Yes or No:

Yes If the non-Mozilla version is designed predominantly for search engine robots to read, No If the non-Mozilla version is designed predominantly for humans to read

In other words, if the non-Mozilla version of the site is designed for humans using a text to speech converter, a Lynx or Mosaic browser, a PDA or WAP phone, an interactive TV set or any other non-Mozilla browser, then the use of Agent-Based Delivery is not spam. It passes this basic test:

Suppose search engines did not exist. Would the technique still be used in the same way?

Note that just because Agent-Based Delivery does not imply spam, this does not prevent Content Spam or Meta Spam being placed on pages served by Agent-Based Delivery. This is analogous to spam being placed in noframes or noscript tags.

We will now define and briefly discuss Agent-Based Spam.