Computer viruses and other “malicious” software is one of the greatest threats lurking in the network. Such viruses can delete our files, slow, or even prevent, the work of the operating system or (which is the most dangerous) send our logins and passwords, for example, for e-mail, or even a bank account, into the hands of unknown to us persons. Of course you can defend against such threats. The basic tool that you will need is an antivirus program. It allows you to not only detect viruses already installed on your computer, but also protects against new viruses from the Internet. Remember that every day new viruses are created and their methods of operation are improved. Therefore, you should update as often as possible the viruses database contained in your antivirus program. Another program that is worth using is the so-called Add-aware. This program protects your computer from applications that send the network information that we want to keep for ourselves, such as passwords or logins. Another good security programs are the ones of Firewall type. As the name suggests, they are kinds of “fire wall” which will protect your computer against external intervention. These programs are much more complicated to use, and their proper configuration should be entrusted to someone who already has some experience in working with the computer. Indeed, if it is badly set, firewall will cause us more problems than benefits by blocking many Internet applications, which are one hundred percent safe. If you use these programs, as well as apply the principle of “common sense“ you should protect the computer from viruses attacking from Internet .