Deep pocket sheets are fitted sheets with larger corners to help it fit a thicker mattress. If you've ever tried to make a bed and had trouble with the corners your sheet probably isn't the right size. If it takes a lot of pulling to get all four corners in place or the corners pop loose when you are sleeping then you know what I mean by trouble.
Buying that fancy mattress isn't the best use of your money if you spend all of your time trying to make the bed. Finding the right size fitted sheets for your mattress will make that new mattress a lot more enjoyable. Sometimes a mattress topper can cause the thickness of your mattress to increase enough to require this type of sheet.
One perk that comes along with deep pocket sheets is that they normally have a higher thread count than standard sheets. The most important thing to look at when buying a sheet is the thread count and this gives you a jump on that part of things. Getting sheets with deep pockets can be a little more expensive than standard sheets but they aren't as hard to find as they used to be. You should be able to find a reasonably priced sheet at many of your local department stores.
Deep pocket sheet sets are made of the same material as regular sheets. Cotton, flannel, and silk are just a few of the possible fabrics that your sheet might be made of. Some people swear by Egyptian cotton sheets.
An alternative to buying special sheets is to think about sheet suspenders. These little gadgets will grab onto the corner of your sheet and force it to stay in place. If money is tight just check the prices of a deep pocket sheet vs. a set of sheet suspenders and go with what makes more sense financially. You may still have to struggle to make the bed but once it is made it will (hopefully) stay made.