When is it Official?

During a discussion about babies walking a couple months ago, a friend of ours mentioned that we would need to determine what, in our opinions, would constitute Caleb as "walking". At that point, Caleb had only taken 1 step a couple of times, so we didn't give it much thought. A few days after that conversation, though, Caleb took 5 steps. (This was five days after his first birthday.) Then he waited a couple weeks before he did it again. Over the last few weeks, he's added several more steps to his attempts at walking. His most recent accomplishment has been 10 steps, which he's done a couple of times.

As I thought about his accomplishment yesterday, it hit me that 10 steps is a lot, and it got me to thinking, "When is it official?" Though he's taken 10 steps twice now, it's not like he's always trying to walk because he definitely crawls the majority of the time. So I'd love your opinions, when do you think you would say a baby is walking?