The only planes we deal with are the following:
The Prime Material
The Prime Material plane is actually the core world, the other planes are actually reflections of it in a way. This is the normal world where hominids are born, live, fight, and die.
The Feywild is the faerie realm that intersects the Prime at points. Fey creatures come from the Feywild. Not all of it is “good” - hags live in the fens and marshes, etc. This is a capricious place and is a changeable and fickle as a river or life itself. There are settlements, towns, and cities. The inhabitants are usually elves, eladrin, or humans that fell into the Feywild and became trapped there. The Archfey that rule realms in the Feywild do so in relative harmony, but there is always scheming and positioning. They work, generally, to promote the wellbeing of hominids in the Prime Material plane through visions and miracles done by their followers, being as they are unable to act directly there.
Shadowfell is the realm of the dark fey/fiends. This is a dark and dreary place bereft of light and life and joy. There is a lake (Gloaming Water) in the Shadowfell that is utterly dark. It is where damned souls are condemned, drifting forever beneath the surface. This lake is also where necromantic power is sourced. There are “normal” inhabitants. There are villages, towns, and cities. Generally inhabited by undead and ghouls in some or mad orcs and goblinkin in others. The Archfiends that rule various realms in the Shadowfell war and scheme against each other and the Archfey of the Feywild. They work to create woe in the Prime Material plane through visions, nightmares, and madness sent to their followers, being as they are unable to act directly there.
Summer and Winter Courts
At alternating cycles, respecting the dichotomy of their parents, there is a truce where the Archfey and Archfiends come together to maintain relations. The Summer Court is held in the Feywild and the Winter Court is held in Shadowfell. When these cosmic events happen, there are invariably ripples in the Prime Material plane.