Embryonic development is the process of how a baby grows inside its mother's belly. Just like how a plant grows from a seed, a baby grows from one cell that is the fertilized egg.
Over the next few weeks, the cell splits into more and more cells, forming an embryo. The embryo starts to take shape, and different parts of the body begin to form, like the head, arms, legs, and heart. Each part of the body has special cells that know what to do and how to grow to make it look just like it's supposed to.
As the weeks go by, the baby continues to grow, and organs like the kidneys and lungs start working. The baby also starts to move and kick as it gets bigger and stronger.
Eventually, after around 9 months, the baby is fully developed and ready to be born. It's amazing to think that all of this started from just one tiny cell!