Now, you can do shopping, get really useful information, and it still is fun. Ever more information is transferred back and forth between a host and a user. The methods of security mentioned above are common knowledge. The firewall is not average user has contact with. A firewall is a system or group of systems that enforces an access control policy between two networks.
Various processes accomplish that.
Firewalls, then, implement an access control policy. Usually, a network administrator decides what kind of access is permitted to what user. That protection is achieved by a computer, router, or other communications device which filters access to a protected network. Slowly some rules are enforced, but still there are many people who find fun in doing some mischief. On the other side, there are people who use the Internet as a serious tool for work.