See if you can recall how many times this has happened to you: you're aimlessly browsing Amazon or some other online store looking for a particular product, let's say, a pair of shoes. You check prices, gather as much information as you can from various online vendors, but ultimately make the decision to not make the purchase.Then you log onto Facebook or start reading the news online. And wouldn't you know it - there's an ad on the side for the shoes you were just looking at! Not only are there ads for the particular pair you're considering purchasing, but there are also ads for similar shoes from the same company. What gives?