What's the difference between inserts, doublers, and liners?
Inserts - typically at least 3 layers, these are the fully absorbent layer of a pocket diaper. These can also be added to prefolds, fitteds, and all-in-ones for an extra layer of protection.
Doublers - Usually 2 layers, doublers only boost existing absorbency. They are not absorbant enough to be used by themselves. They're trimmer than an insert so they aren't as bulky when used with a prefold, fitted, or all-in-one. These can also be added to a pocket diaper.
Liners - Usually 1 layer, liners protect the diaper from rash creams and stains. They also make catching messes easier. Some are disposable and some are washable.