At what age does an infant transition to a toddler?

The transition from infant to toddler typically occurs around the age of 1 year old. This age marks a significant developmental milestone as infants generally begin to walk, explore their environment, and exhibit more independent behaviors. This transition is not solely based on physical development but also includes cognitive and emotional growth, as a one-year-old starts to show more complex social interactions and communication skills. Both "1 year old" and "12 months old" refer to the same age; however, in this context, emphasizing "1 year old" is clearly understood as the milestone marking the transition to toddlerhood.