In many (most) bread instructions we are told when proofing to cover the dough with a clear plastic wrap then cover with a kitchen towel (sometimes dry and sometimes wet and warm). I have even seen instructions to create a proofing box by microwaving a cup of water for a minute, moving the cup of water to a back corner of the microwave then putting the bread pan in the microwave - cover it with a towel - and leave it until doubled in size.
My questions is... what is the purpose of covering the dough? Is it to create a dark environment? protect the dough from contamination while rising? and why a plastic wrap then a towel? and in the case of the microwave proofing box, I presume the purpose of microwaving the water is to create a warm, wet environment and yet covering the dough with a towel protects the dough from the warm moisture.
Can anyone help me understand this?