Many moms worry about their child's development, especially in infancy. But as your child grows and becomes more active, you probably spend more time worrying about what they're getting into than whether or not they are achieving their milestones.

"I was much more worried about my daughter hitting all the milestones in the beginning and I read all the books," says Kristen Madden, a mom from Bluffton, S.C. "But the older she got, the less I read, and after she started walking I stopped being so concerned."

Still, your toddler's developmental milestones are important. Even if you don't have time to think about them until they happen, the following are the top 10 milestones your child will reach in his or her toddler years.

Object permanence is an important cognitive developmental milestone, which means that your toddler knows that an object still exists even when it is out of sight. In infancy, your child would quickly forget a toy or other object as soon as you stuck it in your purse or put it away, which made wrangling the remote and the telephone from him a little easier. But when you try to hide something from an 18-month-old, he will wonder where it is and want to find it.

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