Did you ever wonder what’s behind those math questions on Facebook? You know, the ones that “most people will get wrong.”

Or what about those count-the-triangles picture games, which apparently most of us get wrong too?

What do they have in common with recipes, iPad giveaways, and eye test puzzles?

Most of these posts are part of a scheme called “like-farming.”

Like-farming involves getting people to like a post or picture on a particular topic to gather names for targeted marketing. The targeting is based on such things as your interests or age, and what you are asked to like or share.

When you like or share a post or picture on Facebook, your name and a link to your profile is given to the original poster. This provides access to two sources of information for marketing purposes.

The first is your profile. If you have set your privacy settings so your profile is not public, the poster will not be able to see the information on it – but that isn’t necessary for the scheme anyway.

The second source is your list of friends. The assumption is that your Facebook friends share your interests, so they are potential marketing targets. And, if their privacy settings are set to public, then the company that posted the picture can view their profiles.

These posts often encourage you to share them. “Shares” function similar to “likes” — the original poster gets your name and link to your profile. Commenting on them, such as answering the math question, or typing the word they ask you to so you can see what happens next do the same. Furthermore, your friends may also see a post stating that you have liked or commented on the original and be encouraged to do so, as well.

These lists are either sold to marketing companies, or the pages are sold to new owners who may exploit the lists. This violates Facebook’s terms of use, but you still can find these pages for sale on various web sites.

The price is based on the size of the list. Some sell for as much as $5,000, which gives you some idea of how useful they can be to marketing companies.

The general rule is to simply avoid like-farming schemes.

Many people don’t worry about the effect of reduced privacy. However, consider that all of your Facebook friends may not share your laid back attitude.

Doug Rutherford teaches computer networking and security for Yukon College and three post-secondary educational institutions in British Columbia.