A pocket diaper is any cloth diaper that has a pocket opening. I focused on PUL shells (what is PUL?) with a lining and opening, but they are not limited to just that. There are fleece, wool, and even fitted (non waterproof) varieties as well. Still, the PUL shell with a stay dry lining is the most popular, like bumGenius! 4.0 and Fuzzibunz.
The pocket diaper can have an opening at the back (most common), front, or even in the middle.
Openings can be “hidden,” meaning there is a flap over the opening (ex. bumGenius! 4.0/3.0), completely open at the back (ex. Happy Heiny’s), or the envelope style where they tuck in (ex. Tiny Tush Elite), or they can simply have a slit opening.
Pockets are popular because they are customizable and dry quicker than All-in-Ones but remain convenient. They are also less expensive than most All-in-Ones.
Most pocket diapers come with microfiber inserts, the same material used commonly for towels to clean cars or mop pads. It is cheap and absorbent. You can also find pockets that come with hemp, cotton, bamboo, zorb, and more.
As shown in the video, there are many styles of pockets. Middle closing with velcro or snaps, side snapping, one size, sized, and even dual size (another video).
The biggest drawback of pockets comes when it is time to wash (unstuffing the diaper to allow the insert to be throughly washed) and restuffing it when the diaper is clean and dry. A typical load of pockets (15 diapers) will take 5-10 minutes to stuff. Expect to wash every 1.5-3 days. I have a continuous motion video of washing and stuffing diapers to give you an idea.
In its most basic form, a pocket is still just a shell with an opening for you to stuff an absorbent insert. But wow are there a lot of options!