Cloth diapers: explained
There are many different types of cloth diapers. Choosing which system to use will depend on personal preference, budget, desired convenience and sometimes the size and shape of your baby. Whether or not you plan to use the diapers on multiple babies will also come into play. Many parents find a combination of different systems is ideal. Here is a description of the 5 main types of Cloth diapers: Flats, Prefolds, Fitted, Pocket, All-in-ones. Another thing to consider is one size options.
Flats
Flats are a square or rectangular piece of absorbent fabric that is folded in a certain way around the baby. They can be fastened using safety pins or Snappy cloth diaper fasteners or simply held in place by a snug 
fitting diaper cover. They can be folded in different ways to accommodate your absorption needs. Most commonly, flats are made of cotton, hemp, bamboo or sherpa. Although they are the most economical cloth diaper system, the folding technique does require some time and effort. Flats wash well and dry quickly; very handy when camping or traveling when hand washing might be required. Flats are very customizable and are great for very small babies. They are also very versatile…when your baby is finished with them, they can be used as burp cloths, dish clothes, rags etc. They can also be folded and used as an insert or doubler in other diaper systems. A diaper cover is required.
Prefolds
Prefolds are similar to flat diapers but require less folding. They are made of 3 multi-layer panels sewn together, with the middle layer being the thickest to provided increased absorbency. The absorbency and quality of prefolds depend on the fabric and the number of layers. Most prefolds will indicate the number of layers of fabric used in each panel. For example, 4 x 8 x 4 means the two outside panels have 4 layers (ply) of fabric, and the middle panel has 8 layers (ply). Prefolds can be folded in thirds and laid in a diaper cover, or fastened with safety pins and a Snappy. This system is very versatile as prefolds can be folded and layered in a variety of ways to meet different sizing and absorbency requirements. They are relatively inexpensive and can also be used as inserts in other diaper systems. A diaper cover is required.
Fitted Diapers
Fitted diapers are made of layers of an absorbent fabric, cut in an hour-glass shape. They have built in closures (snaps or velcro) and have elastic waists and thighs to help contain messes. They are usually made from 
cotton, bamboo, hemp, sherpa or velour. Fitted diapers do not require folding or pinning. They are easy to use and when paired with the proper diaper cover can be virtually leak-proof. Some brands tend to be a little bulky, however bamboo and hemp make for trimmer and very absorptive options. A diaper cover is required. Depending on the brand, fitted diapers are available in many sizes as well as one-size options.
Pocket Diapers
Pocket diapers are made up of 2 parts: the “pocket” or diaper cover and the absorbent insert. The outer layer of the pocket is made of a waterproof fabric (usually PUL), while the inner layer is a stay-dry fabric (usually fleece or suedecloth). The two layers are sewn together to form a pocket into which an insert is stuffed. The insert can be made from any absorbent material. Some inserts are made of microfibre, while others are made of natural fabrics such as cotton, hemp or bamboo. Folder prefolds or flats can also be used as insert. When pocket diapers are “stuffed” with an insert, these diapers are just as easy to use as an All-in-one or disposable diaper. Pocket diapers are trim and keep baby’s skin dry and rash free since moisture is wicked through the stay-dry inner layer and absorbed into the insert. The removable insert makes washing and drying very easy and quick. Depending on the pocket diapers are available in many sizes as well as one-size options.
All-in-ones (AIO)
AIO's are the easiest and most convenient cloth diapering system. As the name suggests, they are one piece with built-in fasteners (velcro or snaps)…and are just as easy to use as disposable diapers. These are great 
for baby-sitters or day-care or parents who are new to cloth diapering. AIO's have a waterproof outer layer, a built-in absorbent layer and a stay-dry inner layer. Since the insert is not removable, these diapers tend to take longer to dry. AIO's are generally less customizable since the absorbent insert is built-in. Some brands, like BumGenius, make an AIO with an opening to case you want to add an insert or booster and to speed up drying. Depending on the brand, AIO's are available in many sizes as well as one-size options.
One-Size Diapers
One-size diapers are intended to fit a baby from birth to toilet training. The size is adjusted using snaps and/or elastics to accommodate a growing baby. One-size diapers are available in a variety of brands of fitted, pocket and all-in-one diapers. They tend to be more bulky than sized diapers, especially on smaller babies, but they are an economical alternative to sized diapers since you only need to buy one set of diapers.
