Standing up for himself

Sam has been practicing free-standing for the last week or so. He started letting go of what he was holding and standing for a few seconds before sitting down. Gradually he stood for longer and longer, yesterday doing 15 seconds in a row. He's been learning to sit on his knees and control his way up and down a lot more (no more falling quickly to his butt). Just today he stood up from a sitting position for the first time without holding on to anything! So cool to see. He's also taking steps while we hold his hands. Perhaps bipedal locomotion isn't too far away....