3. Browser malware

Your browser can become infected with malware when you download certain plugins such as tool bar plugins.

This type of malware may not damage your system files, but it can cause inconvenience and ultimately the creators of the malware will be making money from you.

Adware

This malware can force your browser to display unwanted pop-up advertisements. It can cause pages that you didn't request to open up taking you to unwanted web sites. It can also take over your browser home page and direct you somewhere else every time you open up your browser (e.g. a porn page)

Click fraud

Click fraud malware aims to use your computer resources to open certain web sites and send a mouse click to the adverts. Every click makes them money. You are not aware of this of course, as the activity is hidden in the background.

Pharming

When you want to visit a website, you type a web address into your browser. Pharming malware will infect your browser, redirecting you to an identical looking, but fake website. It does this by telling your browser to look for a different IP address to the genuine site to that of the fake website thus redirecting you to the phoney site.

To all intents and purposes the site looks exactly the same to you. The only difference that you might notice is that the URL will be different from the genuine shop's address.

When you enter details such as your user name and password or credit card number the fake website will be recording the information.