Pocket

Pocket nappies are the most popular style of modern cloth nappy available on the market, and they are generally what it sounds - a pocket to the shell of the nappy.
There is normally one or two openings of the shell where an insert is put inside and appears like an all in one style. 

Benefits are that inserts can be removed for washing and you can have more inserts than shells for those colder months.  They can also easily be boosted for night times or as your baby gets older and starts to wet larger amounts.