This age range isn’t just a category, it marks a major shift in how children grow, move, and interact with the world. Around their first birthday to 18 months, babies often take their first steps, and with that mobility comes the nickname “toddler.” By age three, most children have developed a growing vocabulary, emotional expression, and increased independence.
Brain development during the first three years of life is faster than at any other time. This period lays the foundation for lifelong learning, behavior, and health. In fact, a young child is developing 1 million neural connections every second!
The word “toddler” comes from “to toddle,” which means to walk unsteadily. It perfectly captures the way young children move during this stage — wobbly at first, then increasingly confident.
Technically, 3-year-olds are in a transition stage. Some resources call this the start of the “preschooler” phase, but many still consider ages 1-3 to be toddlerhood.
By 18 months, a child is firmly in toddler territory. They’re usually walking, babbling or using words, and showing a strong sense of curiosity.
Every child develops at their own pace. For the first time in nearly two decades, developmental milestones for infants and toddlers have recently been revised by the US Centers for Disease Control and the American Academy of Pediatrics. With this update, the percentage of children expected to meet certain milestones is raised to 75%, meaning 25% of children would not be expected to meet those milestones by that age.
A toddler is a child from age 1 (about 18 months) to 3, experiencing one of the most dynamic periods of growth. Understanding this stage helps parents, caregivers and early childhood professionals support young children in ways that make a lasting difference.
Explore tools to help caregivers understand and approach behaviors such as biting and tantrums.
