Definition from Wikipedia:

Spyware is computer software that is installed surreptitiously on a personal computer to intercept or take partial control over the user's interaction with the computer, without the user's informed consent.

In the context of affiliate marketing

How does spyware work?

Many spyware software will deliver ads, usually in the form of a pop-up. The ads delivered are decided based on the customers online habits delivering ads which are deemed relevant. Ads can be delivered on an adhoc basis, sometimes several every minute or they can be delivered in relation to a site that the user is visiting.

So how could this negatively affect an affiliate campaign?

Spyware could take sales from legitimate affiliates. It would do this by placing an affiliate tag on the users’ activity, with the spyware operator acting as an affiliate replacing any other affiliate tag. For example, if a user was viewing an affiliate site and then clicked on a client to purchase the spyware tag would overwrite the affiliate tag effectively stealing the sale.

This is considered affiliate fraud and is banned by most affiliate networks terms and conditions. For this reason most networks, agencies and clients will ban spyware from their networks.

What is the difference between spyware and adware?

Adware works in the same way as spyware in that ads are delivered according to what the user has been browsing. Unlike spyware adware is downloaded onto a person’s computer with their consent. However, there are grey areas around some adware companies about how aware the customer is of what they are downloading. It is suggested that if a company wants to work with adware companies then they should work with approved adware companies which will act in an ethical manner.

How should a client treat spyware?

Spyware companies are considered unethical both from a user perspective and in the affiliate market so as a client you should have a policy not to work with any spyware companies. Most networks will have this policy in place and will have a list of all known spyware companies. If in doubt contact your network or agency for further guidance.

How can you spot potential spyware / adware on your campaign?

The usual pattern of spyware or adware being use is a very high number of clicks and a very low click through rate and or conversion rate. If you see a spike in an affiliate’s traffic that is abnormal then it is advised to investigate this and ask them how they are generating traffic. Again your network or agency will be able to advise you further on this.