At birth, babies have almost no ability to control their movement. At the age of about four weeks, a baby placed on its stomach can usually hold its head up. At about four months, the baby will usually be able to sit up with support, and at the age of seven months should be able to sit alone.
At around eight months, most babies can stand with assistance, and will start to crawl at ten months. They can probably put one leg after the other if they are led at about 11 months, and pull themselves up on the furniture by one year. At about 14 months a baby can usually stand alone, and the major movement milestone of walking will probably occur around 15 months.
These are average baby movement figures and many children will reach them much earlier and others much later. Physical development does not equate with mental development and parents should not be concerned if their child takes its time about reaching the various stages. Einstein himself was so slow in learning to talk that his parents feared he was retarded.