Early childhood spans ages 3-6 years and is an important period of development. During this time, children experience physical growth and motor skill development. Cognitively, they are in Piaget's preoperational stage, developing the ability to use symbols and representation. Key cognitive concepts developing include time, space, quantity, and relations. Socially and emotionally, children are learning language, emotions, gender roles, and play skills. Common health issues include minor illnesses, major illnesses prevented by immunization, and accidental injuries, which can be influenced by factors like exposure, stress, poverty, and homelessness.