Object permanence is the understanding that objects continue to exist even when they are out of sight. This is a major milestone in cognitive development that typically occurs between 6 and 12 months of age.

Emotional intelligence is the ability to identify, understand, and manage one's own emotions, as well as the emotions of others. It is a key component of social competence and is important for success in relationships and school.

Walking is a major physical milestone that typically occurs between 9 and 15 months of age. It is a sign that the child is gaining strength and coordination and is becoming more independent.

Language acquisition is the process by which children learn to speak and understand language. It begins in infancy and continues throughout childhood. Language acquisition is a complex process that involves many different skills, including listening, speaking, reading, and writing.

Playing with peers is a common social milestone in early childhood that typically begins around 2 years of age. It is important for children's social development as it helps them learn how to interact with others, cooperate, and share.

Empathy is the ability to understand and respond to the emotions of others. It is a key component of social competence and is important for success in relationships and school.

Expressing happiness is a common emotional milestone in early childhood that typically begins around 6 months of age. Infants and toddlers express happiness through smiles, laughter, and cooing.

Self-regulation is the process by which children learn to control their own behavior. It includes the ability to control impulses, manage emotions, and focus attention. Self-regulation is a key component of social competence and is important for success in school and relationships.

Problem-solving is a common cognitive milestone in early childhood that typically begins around 2 years of age. Toddlers begin to learn how to solve simple problems by trial and error. They also begin to use language to describe problems and solutions.

Symbolic representation is the ability to understand and use symbols. It is a key component of cognitive development and is necessary for language, imagination, and creativity.

Crawling is a common physical milestone in early childhood that typically occurs between 6 and 10 months of age. Crawling helps infants and toddlers explore their environment and develop their gross motor skills.

Language comprehension is the ability to understand language. It includes the ability to understand spoken words, written words, and gestures. Language comprehension is a key component of language development and is necessary for communication.

Playing with peers is a common social milestone in early childhood that typically begins around 2 years of age. It is important for children's social development as it helps them learn how to interact with others, cooperate, and share.

Empathy is the ability to understand and respond to the emotions of others. It is a key component of social competence and is important for success in relationships and school.

Expressing happiness is a common emotional milestone in early childhood that typically begins around 6 months of age. Infants and toddlers express happiness through smiles, laughter, and cooing.