Diaper covers are designed to prevent leaks and keep wetness inside the diaper.  Fitted, contour, prefold, and flat cloth diapers do not have an outer waterproof layer and require the use of a cloth diaper cover to prevent wetness from getting onto clothing.  Diaper covers can be made out of waterproof material, fleece, or wool.  There are two main types of diaper covers:  pull-on covers and diaper wraps.  Pull-on styles work well over fitted diapers and prefolds or contours that have been fastened.  Diaper wraps work well with prefolds and some fitted diapers. 

The number of diaper covers you will need depends on the type of diaper cover purchased, how often you plan to wash, and the age of your baby.  In general, you will typically use 4-6 diapers covers per day.  Infants will soil more diaper covers than a toddler.  Some diaper covers like wool diaper covers are only washed every 2 weeks or when soiled.  They can be air dried between uses.  Most diaper covers can be washed with your cloth diapers.  Many will need to hang to dry.  If you plan to wash cloth diapers every 2-3 days and want to save some money you can wipe down or hand wash waterproof covers in between wash days. 

Diaper covers are easy to use.  If you are using a fitted diaper or fastened contour or prefold you can use a pull-on diaper cover.  They go on and off like a pair of shorts.  You can also use a diaper wrap style cover.  Make sure you tuck in any fabric inside the diaper cover to avoid leaks.  If you are using a diaper wrap with a prefold or contour simply lay the prefold or contour in the wrap and fasten it on your baby.

Thanks Mama offers a wide variety of cloth diaper covers.  You can find cloth diaper covers with snaps, cloth diaper covers with Velcro-style closures, one size diaper covers, diaper covers that you can pull-on, as well as wool diaper covers.