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A scraper site is a spam website that copies all of its content from other websites using web scraping. The purpose of creating such a site can be to collect advertising revenue or to manipulate search engine rankings by linking to other sites to improve their search engine ranking.
A search engine is not a scraper site itself; sites such as Yahoo and Google gather content from other websites and index it so that the index can be searched with keywords. Search engines then display snippets of the original site content in response to a user's search.
Made for advertising 
Some scraper sites are created to make money by using advertising programs. In such case, they are called Made for AdSense sites or MFA. This derogatory term refers to websites that have no redeeming value except to lure visitors to the website for the sole purpose of clicking on advertisements.
Made for AdSense sites are considered sites that are spamming search engines and diluting the search results by providing surfers with less-than-satisfactory search results. The scraped content is considered redundant by the public to that which would be shown by the search engine under normal circumstances, had no MFA website been found in the listings.
Scraper sites may violate copyright law. Even taking content from an open content site can be a copyright violation, if done in a way which does not respect the license. For instance, the GNU Free Documentation License (GFDL) and Creative Commons ShareAlike (CC-BY-SA) licenses require that a republisher inform readers of the license conditions, and give credit to the original author.
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||This section may contain original research. (September 2007)|
Many scrapers will pull snippets and text from websites that rank high for keywords they have targeted. This way they hope to rank highly in the search engine results pages (SERPs). RSS feeds are vulnerable to scrapers.
Some scraper sites consist of advertisements and paragraphs of words randomly selected from a dictionary. Often a visitor will click on a pay-per-click advertisement because it is the only comprehensible text on the page. Operators of these scraper sites gain financially from these clicks. Ad networks claim to be constantly working to remove these sites from their programs, although there is an active polemic about this since these networks benefit directly from the clicks generated at these kind of sites. From the advertiser's point of view, the networks don't seem to be making enough effort to stop this problem.
Scrapers tend to be associated with link farms and are sometimes perceived as the same thing, when multiple scrapers link to the same target site. A frequent target victim site might be accused of link-farm participation, due to the artificial pattern of incoming links to a victim website, linked from multiple scraper sites.
Domain hijacking 
Some spammers who create scraper sites may hijack a recently-expired domain name. Doing so will allow spammers to utilize the already-established search rankings for the domain name and incoming links. Some spammers may even try to match the topic of the expired site, to utilize their search rankings for those keywords. For example, an expired website for a photographer may be hijacked by a spammer who would generate a scraper site about photography tips.
See also 
- Black Hat SEO — More about Black Hat SEO technique.