During infancy, babies experience rapid growth in height and weight, gaining approximately 5-7 pounds and 2-3 inches per month.

Imitation is the ability of infants to copy the actions of others, which is a key aspect of their social and cognitive development.

During toddlerhood, children experience significant cognitive development, including the development of object permanence, symbolic thought, and the ability to engage in pretend play.

Negativism is the tendency of toddlers to assert their independence and autonomy by saying "no" or refusing to cooperate.

During toddlerhood, children experience significant social development, including the development of peer relationships, the emergence of empathy, and the ability to cooperate with others.

Emotional contagion is the ability of infants to recognize and respond to the emotions of others, which is a key aspect of their social and emotional development.

During toddlerhood, children experience significant physical development, including increased mobility, development of fine motor skills, and improved coordination.

Toddlers experience significant language development, including receptive language (understanding language), expressive language (using language), and pragmatic language (using language appropriately in social situations).

During infancy, babies experience significant social development, including the development of attachment to caregivers, the emergence of social smiling, and the ability to interact with peers.

Receptive language is the ability of infants to understand the meaning of words, which is a key aspect of their language development.

During infancy, babies develop object permanence, which is the understanding that objects continue to exist even when they are out of sight.

Expressive language is the ability of toddlers to use language to communicate their thoughts and feelings, which is a key aspect of their language development.

During toddlerhood, children experience significant social development, including the development of self-awareness, the emergence of empathy, and the ability to cooperate with others.

Pragmatic language is the ability of toddlers to use language appropriately in social situations, which is a key aspect of their language development.

During infancy, babies develop fine motor skills, such as the ability to grasp objects and manipulate them with their hands.