By 8 to 10 months, babies attempt to communicate with others using gestures and pre-verbal sounds. There are two common ways children do this: 1) declarative gestures–where the baby points to objects or touches them to get others to pay attention to the item; 2) imperative gestures–where infants want something and they use pointing, grabbing, and sounds to get others to grant their requests. Eventually, some of these attempts–like a child lifting her arms to be picked up or panting to indicate a dog–start to act like words.
Acredolo, L. P., & Goodwyn, S. W. (1990). Sign language in babies: The significance of symbolic gesturing for understanding language development. In Vasta, R. (Ed.), Annals of child development, 7, 1