These are sized to fit your baby or toddler and usually come in size 1, 2 or 3 (although many children will be out of nappies before size 3).
There are normal pocket nappies which are sized rather than birth to potty and fitted absorbent nappies that need a wrap over the top such as the little lamb ones in the picture. These come in a range of materials from microfibre to bamboo.
Fitted nappies are much simpler to put on with no rise snaps to worry about and some find the fit better.
The absorbent nappies are super thirsty and can last overnight.
Pros- good fit, the absorbent nappies are super absorbent, easy to put on
Cons - have to buy different sizes, absorbent nappies are bulky,
This is the waterproof layer that you use over fitted absorbent nappies, terries, flats, muslins etc. It is also what the outer part of all nappy systems is called. Usually made from a type of PUL it keeps all the moisture in the nappy.
These also come in other materials such as wool and can either be in the shape of a nappy or a pull up type.