The Feywild

The Feywild is one of two planes parallel to the Prime Material. It is an unnavigable realm of fantasy, forests, and faeries.
The main inhabitants of this plane are the Fey, a classification of rather storybook-like creatures. Sprites, pixies, treants, redcaps, nilbogs, and many others are all of this niche. Some of them are jubilant, eye-twinkling forest spirits. Others are thieving, mischievous miscreants.
The plane has its own air of unrestrained emotion, birthing a very different kind of behavior than what is normal to the Material Plane. Magic, as well, is more potent and uncontrollable than on the Prime Material. For this reason, certain mages draw power from the Feywild, potentially enhancing their magicks. Yet, these methods often backfire, leading to unwanted surges of energy and arcana; it's not a road to be taken lightly. However, rangers and druids, especially, are differently attuned to magic of Fey than most. It is from here that they draw their magic, in a more natural and precautious way than those who try to bend the Feywild to their will. 
Travel to the Feywild, even, is usually more of an accident than purposeful. Wanderers might find themselves there by passing under arching trees, entering the space behind a waterfall, going to sleep in a field of flowers, et cetera. Such nonnative persons might discover that, what was a city in the Prime Material, might be a forest full of life in the Feywild. 
And those who leave the plane will find that time would have passed differently. While the shortest of stays might have little effect on an interplanar traveler, any extended visit there might end up being weeks, months, or years more than expected in the Prime Material. Such 'shocks' might also catch up with mortals, especially those without any Fey ancestry. Lost time could send mortals into immediate exhaustion, hunger, or if enough time has passed, instant death.

Type

Dimensional plane