These techniques involve altering the logical view that a search engine has over the page’s contents. They all aim at variants of the vector space model for information retrieval on text collections.

Hidden or invisible text 

Disguising keywords and phrases by making them the same (or almost the same) color as the background, using a tiny font size or hiding them within the HTML code such as “no frame” sections, ALT attributes and “no script” sections. This is useful to make a page appear to be relevant for a web crawler in a way that makes it more likely to be found. Example: A promoter of a Ponzi scheme wants to attract web surfers to a site where he advertises his scam. He places hidden text appropriate for a fan page of a popular music group on his page, hoping that the page will be listed as a fan site and receive many visits from music lovers. However, hidden text is not always spamdexing: it can also be used to enhance accessibility.

Keyword stuffing 

This involves the calculated placement of keywords within a page to raise the keyword count, variety, and density of the page. Older versions of indexing programs simply counted how often a keyword appeared, and used that to determine relevance levels. Most modern search engines have the ability to analyze a page for keyword stuffing and determine whether the frequency is consistent with other sites created specifically to attract search engine traffic.

Meta tag stuffing 

Repeating keywords in the Meta tags, and using keywords that are unrelated to the site’s content. This tactic has been ineffective since 2005.

“Gateway” or doorway pages 

Creating low-quality web pages that contain very little content but are instead stuffed with very similar key words and phrases. They are designed to rank highly within the search results, but serve no purpose to visitors looking for information. A doorway page will generally have “click here to enter” in the middle of it.

Scraper sites 

Scraper sites, also known as Made for AdSense sites, are created using various programs designed to ‘scrape’ search engine results pages or other sources of content and create ‘content’ for a website. The specific presentation of content on these sites is unique, but is merely an amalgamation of content taken from other sources, often without permission. These types of websites are generally full of advertising, or redirect the user to other sites.