While you can be assured that you need not sit down and attempt in any formal way to teach your child every word he needs to know, there are things you can do to encourage language development—and it's almost certain that you are doing them already!
Language development requires plenty of opportunity for the budding speaker to interact with other people. While a baby might well be able to learn new words from television, for instance, she wouldn't be able to learn to talk simply by watching television. Hearing your speech in response to hers, your baby can enrich and correct her own language.
However, this doesn't mean you need to become the speech police, correcting every mispronunciation or improperly used verb tense. But you can gently and constructively shape your child's speech as you name objects and interact with him. A conversation between the two of you might go something like this:
Mom: "That's right, that's our dog over there."
Mom: "Mm-hmm. Our dog's name is Maggie. This is Maggie's water bowl."
Baby: "Goggie bowl."
Mom: "Good! That's the dog's bowl, Maggie's bowl."
Getting your child involved in conversation is the most important way to stimulate his language development. The mom in the foregoing conversation follows the baby's lead, helping him develop a sense that he is valued and has something important to contribute.
You may have noticed that when you speak to your child, you use a high-pitched tone of voice, you speak more slowly, and you tend to repeat key phrases or words. This style of speaking is known as motherese. Although motherese is especially prevalent when talking with young infants, it's fine to continue it with your 1-year-old. Just refrain from baby-talk words that don't exist ("goo-goo") and concentrate on the singsong, melodious intonation that's so soothing and enchanting to your little one.
No matter how often you may hear that it is normal for children to develop linguistic skills at different paces, you may find yourself worrying from time to time about your own child's language development. It is never inappropriate to express concerns about your child's development to your pediatrician. You might particularly want to call your physician's attention to your child's speech and language if he does not produce any recognizable words by the time he is 16 to 18 months old.
Inquire, too, if your child develops language skills but seems to lose them after an illness or high fever (some regression is normal here, but recovery of skills should be rapid), if he can't follow simple, one-step directions ("Put your cup down on the table") by 18 months, or if at any time he seems to have difficulty hearing things.