Its called “Like Harvesting” and its a way for people or organisations to boost their facebook pages allowing them to target larger audiences with subsequent adverts or to sell likes and potentially your profile information to third parties.

Usually these will be a picture, maybe a small girl with a sign saying things such as “my mum says if I get 200,000 likes then I can get a pony”, a picture of a sports car/iPad/high value item with a bow on it pretending to be a competition or more often than not a high value voucher offer for a supermarket or similar.

Its not going to hurt you but think before you share anything on Facebook, try and make sure posts are not created purely for likes and check out the person posting it to see if their page looks legit.

Finally, if the offer seems too good to be true then it probably is!