Cutaneous respiration of frog is the mechanism through which amphibians breath.instead of using gills they use the skin to breath.their skin must always be moist to allow efficient respiration.they absorb oxygen from the water through their skin using special blood vessel.
while completely submerged all of the frog respiration takes place through the skin. the skin is composed of thin membranous tissue that is quite permeable to water  and contains a large network of blood vessels
the thin membranous skin allows the respiratory gasses to readily diffuses directly down their gradient between the blood vessels the blood vessels and the surroundings.
when the frog is out of the water mucus gland in the skin keep the frog moist which  helps absorbs dissolved oxygen from the air.
can you plzz pick it as bst
respiration through skin surface is known as cutaneous respiration.this type of respiration is usually seen in some insects and also in frogs.there are pores on the skin of frogs through which they take in air only when they are in water.but when they are on land , they use their lungs to respire.