What is an advert link?

I get emails that appear to come from one of my contacts but its a link to an advert and not from my contact?

• Does anyone know what this is and how they get details of my contacts

• Answer:

  It sounds like your friends e.mail account has been compromised, most likely because they clicked through to a website which was infected with a trojan or virus, Their e.mail account is now being used to send out spam, starting with all the contacts in their address book. If you've clicked on the link then chances are you've infected your own computer. The virus or trojan will be sending back all your details to the hackers, including user-names and passwords for websites you've visited and online banking details, all worth their weight in gold to an identity thief. Do not log into any websites that require a user ID and password. Do a complete virus scan on your computer right away and tell your friend to do the same asap.