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Repeating the search engine registration process one or more times for the same page or site. Under certain circumstances, this is regarded with suspicion by the search engines, as it could indicate that someone is experimenting with spamming techniques.
The Infoseek and Altavista search engines are particularly vulnerable to spamming because they list sites very quickly, and are thus easy to experiment with. Both engines de-list sites for repeated re-submission and Infoseek, for example, does not allow more than one submission of the same page in a 24 hour period. Occasional re-submission of changed pages is not normally a problem.
Sometimes expressed as the percentage of the universe of a target audience, however it is measured by the total number of unique users who will see the ad over a specific period of time.
Related to precision, this is the degree in which a search engine returns all the matching documents in a collection. There may be 100 matching documents, but a search engine may only find 80 of them. It would then list these 80 and have a recall of 80%.
Nepotistic link exchanges where websites try to build false authority by trading links, using three way link trades, or other low quality link schemes. When sites link naturally there is going to be some amount of cross linking within a community, but if most or all of your links are reciprocal in nature it may be a sign of ranking manipulation. Also sites that trade links off topic or on links pages that are stashed away deep within their sites probably do not pass much link authority, and may add more risk than reward. Quality reciprocal link exchanges in and of themselves are not a bad thing, but most reciprocal link offers are of low quality. If too many of your links are of low quality it may make it harder for your site to rank for relevant queries, and some search engines may look at inlink and outlink ratios as well as link quality when determining how natural a site's link profile is. See also: Indexing Timeline - Matt Cutts states that sites which have many low quality inbound links and / or outbound links may struggle to rank or even get deeply indexed by Google. Live Search: Linkdomain:SEOBook.com LinkFromDomain:SEOBook.com - shows SEOBook.com's reciprocal links What a Links Page Should Not Look Like - article by Jim Boykin
A method of alerting browsers and search engines that a page location moved. 301 redirects are for permanent change of location and 302 redirects are used for a temporary change of location.
where the Internet user is automatically taken to another web page address without him/her clicking on anything. Redirects are generally not good for search engine rankings, as they dilute PageRank. There is also the risk that the search engine spider will not follow your redirect.
Fees paid in exchange for delivering a qualified sales lead or purchase inquiry. For example, an affiliate drives traffic to other companies' sites, typically in exchange for a percentage of sales or a flat referral fee.