How do frogs breathe and drink through their skin?

A photo of a frog raising its head above the water with its reflection below.

Unlike humans, frogs and other amphibians don't need to rely on their lungs to breathe; their unique skin helps them exchange oxygen and drink. But how do frogs breathe and drink through their skin?

Frog skin is complex: It's thin, covered in glands that produce mucus to keep the skin moist, and porous enough to allow air molecules to permeate.