I know what a bottle is because mommy and daddy always say "bottle" and show it to me before they feed me. About three weeks ago, I started saying "Ba" when I was hungry. Mommy and daddy thought it was just coincidence, but then they noticed that I would only say it when I am hungry. And they also noticed that I looked directly at them when saying it, as if to drive home the point that I was trying to communicate with them.
Grandma and grandpa came over the other night. Grandma was playing with me, and I looked at her and said "Ba." She laughed and kept playing with me. A few minutes later, when she hadn't fed me, I looked directly at her and said "Baaaaaa." She laughed again, and kept playing with me, but again -- no bottle! So finally, I looked right at her, and said very forcefully, "BAAAAA!" She finally got the point and said "Okay, okay!" and gave me to mommy, who then fed me.
And that's the story of my first word. Or at least partial word. But be sure of one thing -- I know what I want, I'll tell you what it is, and you'd better do what I say.