Embryonic development is the process by which a fertilized egg, or zygote, transforms into a fully formed organism. This process begins with cell division, where the zygote divides multiple times to form a cluster of cells called a blastocyst. As development continues, these cells differentiate into various types, forming the basic structures and systems of the body. During embryonic development, three primary layers form: the ectoderm, mesoderm, and endoderm. Each layer gives rise to specific tissues and organs. For example, the ectoderm develops into the skin and nervous system, while the mesoderm forms muscles and bones. This intricate process is crucial for the proper formation of a healthy organism.