Pa4.info that focus on WWW traffic are called web filters. Many organizations ? including schools, corporations, and countries ? use p**** servers to enforce acceptable network use policies (see content-control software) or to provide security, anti-malware, and caching services. A traditional web filter is not transparent to the client application, which must be configured to use the filter (manually or with a configuration script) .The other main purpose a p**** server is to filter what is allowed into the network. While HTTP, FTP, and Secure protocols can all be filtered by a proxy server, HTTP is the most common. Furthermore, administration of browser configuration can be a burden for network administratorsThe proxy server can limit what Web sites users on the network can access. Many organizations choose to block access to sites with objectionable material such as hacking information and pornography, but other sites can be filtered as well. If an employer notices workers are spending too much time at sites like eBay or Quicken.com, those sites can be blocked by the proxy server as well..