The importance of internet security today cannot be overstated. There are various threats to security as well as security measures which can be taken.

In Windows, more than one million different viruses are presently active. Botnets are computers used to generate spam, relay viruses or flood a network with requests to cause it to fail. Keylogger, a system for logging user activity, can unintentionally become part of a botnet.

These potential problems can be limited or prevented using protective measures:

Security passwords should be used in machines on network.

Virus protection should be used on certain operating systems such as Windows.
A firewall is a device designed to permit network transmissions based upon a set of rules. This provides a screening system able to protect networks from unauthorized access while allowing legitimate communications to pass.
If network administrators lock down client desktops, it means that users can perform only certain operations. “Lockdown” also refers to a computer or service to prevent unwanted intrusions such as viruses or spam.

Wireless networks present unique security problems which need to be separately addressed.