Before being presented to a human user, an information filtering system removes redundant or undesired information from an data stream using (semi)automated or computerized processes. Its primary purpose is to reduce information overload while increasing the semantic signal-to-noise ratio. Filtering is an important part of any website. Filtering can mean something different on every site. Whether you want to refine the way something shows up on your site, or you want to trim down something; filtering is an every day part of running a business.