At about 4 months, babies can roll from side to back or back to side and at approximately 6 months can turn completely over when laid on their backs or stomachs. At 7 months babies can pull themselves up in their playpens, and they begin crawling using their arms to drag themselves along the floor. At 8 to 10 months, babies begin creeping on their hands and knees and this allows them great freedom of movement. Somewhere around 9 to 11 months, babies walk when led. During this same time, they'll move from standing to walking while holding on to furniture or other support.
Some babies stand alone and even walk at twelve months.
For other babies, neither of these skills is accomplished until 15 months. Walking either as early as 12 months or as late as 15 months is normal. They can creep down stairs and seat themselves in child-size furniture. They are generally more sure and nimble on their feet than before. They alternate feet while climbing stairs, can ride a tricycle, jump and balance on one foot.