A disposable nappy/diaper is for babies or incontinent adults, it absorbs urine and contains faeces, once soiled it is thrown away.
Pampers and Huggies are the 2 most well know brands of disposable nappies, disposables have been around since the late 40's and have changed considerably since then from simple paper pads that fitted inside plastic pants, to the high tech product they are now.
All nappy brands have theire little gimmics to sell the nappy, eg resealable tapes, stretchy waistbands, leak gaurds, wetness indicators and so on, but they all have the same basic make up, consisting of a layer of cloth like material, which is actually thin strands of plastic woven together, this is often called a one way liner, this allows the babies (or adults) urine to be absorbed into the absorbent padding inside the nappy, but also stops it from coming back through so keeping the skin dry,
The absorbent padding layer is made from wood pulp, which are tiny fibres of wood which have been purified to make them white, spread within the fibres are crystals of a absorbent polymer, which turn into a gel when they get wet, this helps the nappy to absorb lots of urine without leaking, as once the wetness is gel, it cannot be squeezed out, unlike the older disposables which only had wood pulp padding, whenever baby sat down it just squished out and left the baby sitting in a puddle!
The last layer is waterproof plastic, this further stops leaks and also acts as a shell to keep the padding contained.
Most disposables nappies apart from the cheapest brands have cute pictures on the front, sometimes companies, Disney for example, pay the nappy manufactor to display there cartoon characters, this is ussualy on the bigger brands, on cheaper brands images like teddy bears and other babyish items are seen.
i saw a baby wearing a disposable nappy