How do babies learn to talk?

A baby arrives knowing zero words. Can't ask for milk, can't say "hello," can't even tell you their diaper is wet. But somehow, by age three, that same kid is chattering about dinosaurs and demanding pancakes. How does a brain go from silent to non-stop talking in just a few years?
It starts with listening. For months before a baby says anything, they're soaking up every sound around them like a sponge in a rainstorm. Your voice, the dog barking, the doorbell, the theme song to that show you watch — all of it pours into their ears, and their brain is busy sorting: which sounds are language, and which are just noise?
