I used to always find the practice of identifying a young child's age mystifying, and, I confess, annoying. "How old is your daughter?", I'd ask a mother. "21 months" she says. Twenty-one months? What the hell does that mean?!
I since learned that everything in childhood prior to the age of two is described in terms of months. You can't escape it --clothing size, toys, jars of baby food, dosages of medicine, and on and on it goes. It's daunting, however, for those who aren't immersed in a child's world. What crazy person came up with this annoying counting method reserved for parents and people working in the kid world? So, let's see... that makes me 420 months old! In "the old days" I secretly resented having to do the math in my head, especially since math has never been one of my strong suits. Sure, I could figure it out... 12 months in a year, 24 months in two years. 24 - 21 = 3. So, the kid is 3 months away from turning two years old, and I'm one day closer to death by the time I arrive at his age calculation. Thanks for the arithmetic gymnastics, lady.
Now, I get it. These little guys grow so quickly and their learning curve is so steep in the first two years, that it makes more sense to those who are firmly in "kid world" to refer to age in smaller units of time than years. Now, when someone says that their child is 3 months old, I know that the child is probably not teething yet, or sitting up or working on his pincer grasp. I know this because now I know what to expect in terms of development of a child at that age.
Now that I get it, I might try to take it easy on non-parents. What's the harm in just rounding off to the nearest year, or half year? It's not like they know the difference. I'll consider it my good deed of the day, and maybe it'll save someone's brain power for another important task, like trying to figure out the phone bill.