Cradle cap, also known as infantile seborrheic dermatitis, is a common thing that can happen to babies. It's when they get these yellowish, greasy flakes on their head, sometimes even on their eyebrows and eyelids. But don't worry, it's no big deal and definitely not something contagious.
Nobody really knows why it happens, but it's probably because their little oil glands go into overdrive and make too much sebum, which is this waxy stuff that hangs out on the skin. Then all those dead skin cells stick together and form those flaky scales. It's not because they're dirty or allergic to something, so don't blame yourself!
Cradle cap usually shows up when the baby is a few weeks old and can stick around for a while. Sometimes it comes and goes, but eventually, it goes away on its own without needing any fancy treatments. Just make sure to keep the baby's scalp clean by gently washing it with a mild shampoo. You can also use a soft brush or comb to gently massage their head and get rid of those flakes. But be nice and don't scratch or pick at it because that can make the skin irritated and maybe even infected.