Navigating the Foreign Language of Cloth: Cloth Diaper Types

First - in ANY CDing situation, you need two things - something absorbent, and something waterproof that will keep the diaper from leaking.  Those are the basics.  Here are the different types of CDs, starting with simplest to more complex/convenient.

Flats

These are large, single layer sheets of cotton that you fold up into different configurations (think origami!) and then fasten them to your baby with pins or a Snappi.  They are not waterproof (require a cover).  

Pros: The cheapest option out there, especially because you only need to change the cover if it gets soiled with poo - hence don't need many covers. Easy to clean and they dry very quickly.  
Cons: Require a little bit more effort than some other options, and can take longer to put on a squirmy baby. Can be bulky. Not necessarily an easy option for daycare providers or other people who may be taking care of your babe. 

Prefolds (PFs)

Think your old fashioned big square of cloth - used to be fastened with pins.  In fact, this is likely what most people envision when you excitedly tell them you are going to cloth diaper your baby!  These are similar to flats, except they are prefolded in the middle, so as to aid absorbency, and you wrap them around your baby, securing with a pin (not super popular, but some people do use them) or with these things called snappis (similar to the fasteners that you can use with ace wrap bandages).  Another option is to tri-fold the PF and lay it in a cover.  This is the absorbent part, so you'll need something waterproof to keep any wetness from going everywhere - used to be rubber pants, no longer.  There are a wide variety of different types of covers you can use - some are super adorable.

Pros: Super cost effective
Cons: Can be tricky to get the various folds right or comfortable for you, two pieces - can be a little annoying/cumbersome

Fitteds 

Fitteds are made entirely of absorbent, natural fiber materials such as cotton, bamboo, or hemp, and they are in the shape of a diaper already (as opposed to having to fold a flat or PF into a diaper shape).  Like flats and PFs, these are also just the absorbent part, but the big difference is the shape - a fitted diaper is FITTED in the shape of a diaper.  Fitteds often come with snaps, so you don't have to worry about pins or snappis, but it is ONLY the absorbent part - you'll need a cover (see link above for examples) to keep from getting everything wet.

Pros: Easy with snaps, less work than a flat or pf, the overall absorbency (the entire diaper) makes this a great nighttime option
Cons: Still requires a cover, can sometimes take a while to dry, can be bulky

Pocket diapers 

We are moving into diapers with increased convenience - pocket diapers, which are a very popular choice, and looks and functions with the same level of ease as a disposable diaper.  A pocket diaper is a washable, reusable diaper with two parts:

1. A waterproof outer layer (PUL) with a synthetic stay-dry inner layer (microfleece, suedecloth, etc.)
2. An absorbent insert, which can be made of microfiber, cotton, bamboo, hemp, etc.

This is the first one-piece diaper - whereas with the flats, prefolds, and fitteds, you needed a cover to make it absorbent, with pocket diapers, the exterior is waterproof, so you don't need an extra cover, and you stuff the absorbent inserts into the shell.  These can be pretty convenient - once they are stuffed, you don't have to do anything else, just grab it and throw it on the kid.  You usually have your choice of velcro or snap closures - super easy.    Velcro is a popular choice because you can get a really personalized fit on your baby, super easy for all users.  Snaps are also popular as they tend to last longer than velcro (which can pill up, get fuzzy, lose it's stickiness overtime), as well as they tend to be tougher to escape from once those little hands get a little more skilled.

Pros: Customizable - if you need more or less absorbency, you just add it or subtract it, super easy once they are stuffed (ie once they are clean, stuff them all right then) - just grab one and go - as easy as a disposable diaper, you don't need a separate cover, tend to be trimmer than other options  

Cons: Some people dislike having to stuff, some babies are sensitive to the synthetic stay-dry material lining the interior of the diaper (suedecloth - used by Bumgenius - tends to be the one that SOME babies are sensitive to)

All-in-ones (AIO) 

What the name implies - all in one piece.  These come with a waterproof exterior, with the absorbent part of the diaper already sewn in and does not come apart.

Pros - Super convenient for those who may not want the extra step of stuffing a pocket diaper or folding prefolds
Cons - Can take a really long time to dry, and unless they have a pocket to add extra absorbent material, you can't customize it to your needs (ie if you have a heavy wetter and need more padding.

All-in-twos (AI2) 

Also what the name implies - two pieces, but all in one package - often has a snap-in pad or something that is your absorbent material, with the waterproof exterior.

Pros: easy, can reuse the shell (sometimes) if it isn't messed on
Cons: can lack the complete customization of other systems (ie needing more absorbency)

Inserts

These are the absorbent material that is inserted into the opening in pocket diapers. In many mainstream cloth diapers, this is a rectangular, multi-layer piece of microfiber. Microfiber is a very thirsty synthetic fiber that quickly pulls liquid into it. It should only be used in a pocket diaper and not directly against baby's skin, as it can dry out and irritate the skin.  Hemp, cotton and bamboo are also used for inserts. These are often slower absorbing, but particularly hemp and bamboo can hold more liquid in general than a microfiber insert of the same thickness. Therefore, it can be a trimmer and more absorbent option, along with being a natural fiber.  Many people will double up with a hemp or bamboo insert topped with a microfiber insert in a pocket diaper for night time use.  

Covers

This is the water proof part - you put it over diapers that don't have a water proof barrier built in - so this would be used with flats, prefolds or fitteds.  Covers are generally made of one of these three materials...

PUL:  Synthetic waterproof covers that usually have snaps or velcro and are a very trim cover option. Rarely leak and you only need a few covers, as you can re-use them between changes if they are only wet. 

Wool: A natural fiber that is breathable and keeps baby's bum cool.  Very popular for use at night over fitteds, though many also use it during the day. When lanolized they are effectively waterproof and require very minimal washing (do not have to be washed after each use).  Can be quite expensive, but upcycled (made from other wool items such as sweaters) instead of newly knitted wool covers, shorties and longies are a more affordable option.  Have to be hand-washed separately from your other clothes and diapers. 

Fleece: A cheaper alternative to wool that is also quite breathable and soft. Has to be washed after each use, but can be machine washed. Can have compression wicking when pressure is applied and can retain odors.