Retailers are using free money as a way to get you inside their stores.
For example, Buy five items and get a $10 giftcard.
However, socking that card away might be a bad idea.
Consumer protection laws apply to gift cards you actually pay money for, not ones given to you for free.
Free cards are considered a promotion or sale and those cards could expire after a certain period of time -- leaving you with $0.
Make sure you read the back of the card for the fine print and find out if and when that money expires.