I am often asked why Facebook sometimes displays questionable ads because a friend of yours “liked” it. Except you know your friend has never played online poker, ordered foreign pharmaceuticals, or taken out a payday loan. Why would Facebook assume your friend, and you by extension, is interested in these things? Simple: “Like Farming.”

Like farmers create Facebook pages and create content dedicated to collecting as many “likes” or “shares” as possible. A simple “brain teaser” that only “geniuses” can solve, a nostalgic image of the past, or fake contests that you have to like to enter are common fodder for link farmers. And since Facebook’s algorithms place a high value on popularity, highly liked and shared pages have a much higher chance of appearing in your feed and being seen by your friends and family.

Once the farm has grown a high popularity rating, the farmer either removes the page’s original content and replaces it with something more nefarious (usually malware or scam advertising) or they outright sell the highly liked page to a third party.

Now instead of liking a page for “your chance to win $5000 from Bill Gates,” you are now a fan of online gambling, for example.

Many like-farmers rely on appeals to emotion: anytime you’re urged to “like” or “share” a post that pulls at your heartstrings there’s likely a like-farmer behind it. “This poor little girl with cancer lost her hair to chemotherapy — ‘like’ this post to let her know she’s still beautiful!” “This new government policy is outrageous — ‘like’ this post if you’re outraged, too!”

If you are unsure whether a page or post is legitimate there are a few places to go to verify the pages information before hitting the like button. Snopes.com is a website dedicated to dispelling rumours and lies that spread online faster than the common cold. Another good site is facecrooks.com which keeps you up-to-date on Facebook scams and provides information about how to protect your privacy.

While Jesus said in the Gospel of Luke, ‘No one who puts a hand to the plough and looks back is fit for the kingdom of God.’ On Facebook, it is a good practice to periodically look back and weed through your past “likes.” You might be surprised to notice you really don’t like some of those things at all.