First, a good antivirus protection is essential these days if you do not want to risk losing everything on your computer. The computer remains, whatever one may say, an expensive investment and know that a simple malware can cause slowdowns, disable your computer, or even damage your equipment.
However, a virus can only be effective if started regularly updated over the Internet. Indeed, the antivirus software in its overall operation, detects only the viruses it knows. It must constantly keep abreast of the latest viruses circulating on the Internet to be able to neutralize them. If you install antivirus software that you purchased a year ago and you do not do the updates, the program's effectiveness may be zero.
A virus can enter your computer in several ways. Either you bring yourself by inserting a CD of uncertain provenance or copying files from a USB key. Either you download from the Internet without knowing it. The peer-to-peer exchange between individual vectors are formidable. Behind the names of known software supposedly pirated and therefore attracting lust, sometimes hide programs or games that contain a virus. When you download new programs for your computer, so prefer to go on sites that have stores rather than on an obscure web page at extending an unknown country.
The third way of getting a virus is of course the receipt of an email. You must be very careful when you look at an attachment, the files included with the message that sometimes are programs. Bring your attention to the extension that carries the name of the file that you are proposing. Upload an image is not dangerous, as, for example, a virus will attempt to impersonate an image. It took him two extensions such as: super-image.jpg.exe (actually, the last extension that counts. Here, it is therefore a hidden agenda and a priori malicious).
Some emails can infect your machine just because you have open. Therefore prefer to configure your email receipt to not display the email or the beginning unless specifically requested by you. So you can filter emails with a subject suspiciously like those that appear to be an email response when you've never written to anyone. Know that your friends can be infected and thus not be aware they send you emails with viruses. In general, do not download an attachment that you did not ask yourself. And if you're in doubt, contact your friend for reassurance.
Finally, a rule of common sense: take regular backups of your important data. If an expert can restore your computer after the passage of a virus, it is not sure he will be able to save your data files. Indeed, the only sure way to completely get rid of a virus is to reformat your hard drive, that is to say, erase completely.