Amazon knows a lot about your shopping habits. Of course, it knows what you buy and have shipped to your home, but the company also knows what you've been searching for, adding to your cart, removing from your cart, and have on your secret shopping lists.
Odds are you're already signed up to receive free samples from Amazon, so you shouldn't have to do anything to sign up. However, if you want to check your accounts status, or if you find the idea of Amazon randomly sending you free stuff to be too much, you can opt out with a couple of clicks.
First, visit Amazon's Sampling Preferences page. There, you'll need to select your preferred sample setting and click Update.
Next, you'll need to visit your account's Communication Preferences Center page and opt-in to Marketing Information by Post if you want to ensure you'll receive samples. Again, click update when you've adjusted the setting to your liking.