Water is another good analogy. When you turn on a tap/faucet, the water that comes out is the water that was just sitting there in that last few inches of pipe,

Water is another good analogy. When you turn on a tap/faucet, the water that comes out is the water that was just sitting there in that last few inches of pipe, it didn't come all the way from the city's dam in that time. Also with waves in water; put a ball floating at the beach and it'll mostly stay put bobbing up and down. (It's only when the waves actually break that there is substantial movement of actual "bits" of water.)