1. Content Spam

With the help of this Spam technique not the searchers but only the search engines can view some part of the data in a web resource (e.g. the of a HTML document).

Some commonly used content Spam techniques are as follows:

a) Invisible text

Using fonts that are the same or similar color as the background to hide keywords is one of the most common search engine spam techniques. This can be done by using tables or a background with a different color than the real background for the site.

b) Keyword stuffing

Another very popular search engine spam trick, used along with hidden text, is the repetition of keywords on the bottom of the page in very small fonts.

2. Meta spam

In order to manipulate a search engine's relevancy calculations, Meta data (which actually describes a web resource) describes a web resource inaccurately or incoherently.

Following are the common Meta spam techniques:

a) Unrelated keywords

In order to fool searchers it has become a common technique to use popular keywords that do not apply to the site's content. For the time being one may be able to trick a few people searching for such words into clicking at the link, but soon they will leave the site when they will not get any relevant information on the topic they were originally searching for. This kind of search engine spam upsets both the search engines and their users.

b) Hidden tags

The use of keywords in hidden HTML tags like title tags (For example: ), comment tags, Meta description tags (for example: ), style tags, http-equiv tags, hidden value tags, alt tags, font tags, author tags, option tags, and no frames tags (on sites not using frames) are considered as search engine spam by some search engines while others may allow it.

3. Identical pages

Duplicate web page (or doorway page) are considered as search engine spam by all search engines and directories. It is not advisable to give the copies different file names, and submit them all (mirror pages). This will be interpreted as an attempt to flood the engine.

4. Code swapping ("bait & switch" technique)

This means optimizing a page for high search engine position, and then swapping another page in its place once a top rank is achieved. This technique does not lead to a long-lasting search engine placement.

5. Page redirects

Redirecting is defined as taking a searcher from a page designed only for a search engine to see to a page designed for the searchers by using META refresh tags, CGI scripts, Java, JavaScript, or server side techniques. This is considered as spam.

Spam filled web pages are intended for the search engines only. When visitor visits those pages, they are redirected to the real page. Generally search engines do not like pages that take the user to another page without his or her intervention.

6. Link farms

Link spamming is the technique of artificially increasing the link popularity of a web site in order to influence its ranking in the search engines.

The common factors of link popularity are

>> the number of inbound links a web site has,
>> the link popularity of the sites linking to that web site,
>> the context of the sites which are linking to the web site, and
>> the similarity with the linking site.

The last three factors are difficult to influence, but web masters still try link-spamming techniques.

Some common techniques are described below.

Posting messages to various message boards and guest books is a very common practice that a web masters implement. They visit hundreds of them and post messages with links to their sites. Search engines are sophisticated software’s and are easily able to detect this sort of spam.

In guest books and message boards, many messages are posted every day. It means that apart from linking to your site they are linking to numerous other web sites. So the number of their outbound links is numerous, this reduces the importance of those links. If there is a web site that has got only two outbound links and it is linking to your site, that link is more important as compared to a link from a site, which has got 200 outbound links.

Though the definition of link popularity says that it is the number of web sites linking to a web site, still it is not the number but the quality of the links that matters. Quality of the links means the context of the links as well the link popularity of the sites, which are linking, to that web site. However, it is very difficult to artificially get quality links.

Another common method by which spammers try to influence the link popularity of web sites is by joining link farms. A link farm is a network of web pages, which are heavily cross-linked with each other. Those web pages are present may be in more than one domain or in more than one server. In order to influence the link popularity, when a web site joins such link farms, it gets a link from each of these pages and in turn it also has to link back to each of those pages. But search engines can detect the link farms as well as the web sites participating in the link farms very easily.