From birth to an age of approximately six months, the infant is considered as being in the prelinguistic stage, which is marked production of sounds such as crying or laughing.
From six months to twelve months, the infant is generally in the babbling stage. At this stage, the child makes sounds that may be parts of human spoken languages, but the sounds are not related to any meaning.
From twelve to twenty-four months, the child is considered as being in the one word, or holophrastic, stage, uttering isolated, recognizable words in his/her primary language.
From twenty-four to thirty-six months, the child progresses to the two word stage. Two word phrases convey meaning; the child's vocabulary expands rapidly in this stage. During this age span, the child will go through the telegraphic stage, using short (but longer than two word) phrases which have no grammatical refinement but are effective communication.
By the age of three years, most children have reached the stage of fluent speech.