Ways how viruses may get to your PC
It is frequently too late for many users to read an article like this one since the most frequent reason why we become concerned about the viruses is because something wrong already happened to our computers. But it may be useful to know basic ways of how viruses spread to prevent future problems.
It is very easy to transfer a virus in e-mail. You just need to attach it to e-mail and send it to someone. Definitely not many people would do it on purpose and that's why modern viruses are able to scan your contacts and send themselves to all of them without your consent. Just imagine what happens when you have 500 e-mail contacts and each of your friends has 500. It is already 25,000 people. And if you add another layer of friends you will get 12,500,000 people. That's why viruses could spread extremely fast via this channel.
But situation is getting better now since many of online e-mail providers automatically scan e-mail attachments for viruses and quarantine all suspicious correspondence.
Internet
Don't download anything from websites which are not 100% safe. Every download even if it is not executable file could contain a virus.
There are some types of viruses which even don't need to be downloaded as an executable file to infect your computer. They will be executed at the moment you open infected website and load an image with a virus code embedded in it. Such viruses are rare though and software vendors try to fix holes which they use as quickly as possible.
Pirated software
Another way how viruses spread is pirated software. Despite of all the efforts of police there are millions of pirated disks produced and bought every year. And vast majority of these disks contains Trojans and other types of viruses embedded in the software. This is just one more reason not to buy pirated software.
Network
Unless you have up-to-date antivirus software installed you're always at risk of being infected by virus through the network. There are lots of holes of how viruses could get to your computer and there used to be times when it took just 2 minutes for fresh computer connected to the network to be infected. To prevent this kind of infection make sure to have latest operating system software with all updates on your computer. Also having good antivirus software is the best way of prevention.