An Information filtering system is a system that removes redundant or unwanted information from an information stream using (semi)automated or computerized methods prior to presentation to a human user.
Its main goal is the management of the information overload and increment of the semantic signal-to-noise ratio.
To do this the user's profile is compared to some reference characteristics. These characteristics may originate from the information item (the content-based approach) or the user's social environment (the collaborative filtering approach).
Whereas in information transmission electronic filters are used against syntax-disrupting noise on the bit-level, the methods employed in information filtering act on the semantic level.
The range of machine methods employed builds on the same principles as those for information extraction. A notable application can be found in the field of email spam filters. Thus, it is not only the information explosion that necessitates some form of filters, but also inadvertently or maliciously introduced pseudo-information.
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