Content filtering
Filtering of websites or email by content type
Content-filtering software blocks access to websites based on the type of content contained on the site. Many techniques may be used to achieve this, including URL filtering, blacklists, and more sophisticated analysis of keywords, image patterns and even layouts of sites to deduce their likely subject matter.
This allows companies to apply corporate policies, such as not allowing employees access to games, gambling or pornographic sites, and is also a major component in parental control systems designed to protect children from inappropriate content.
In some circles such filters are seen as unwanted censorship of the Internet, spawning the term 'censorware' to refer to such filters.
In the context of spam filtering, content filtering describes the technique where the filter decides from the content of the email whether it is spam or ham. Examples of content filtering are Bayesian filtering and Markovian discrimination.
