Anonymizers are tools that allows or attempts to allow users to make their online activity untraceable.

Anonymizers are proxy servers effectively which acts as intermediary between the client and the actual server. Anonymizer attempts to provide a shield of anonymity by protecting the identification information of the actual systems that are using the service or resources.

There are various types of anonymizers that are available freely and commercially on the Internet. There are protocol specific anonymizers which only understand a specific protocol and can only mediate connections that user that particular protocol.

The manner in which this works is that the client would initiate a connection to the anonymizer. The commands that are sent to the annonymizer are sent inside a message.

The anonymizer, on receiving the command, would strip out the commands and relay the connection information to the destination server as if it were originating from the anonymizer.

There are protocol independent anonymizers as well which effectively tunnel the traffic between the server and the client. The protocols that may be used by anonymizer services include openvpn, pptp, socks4, socks5, etc.