By age
Speech at three years
By three, most children hold short conversations and most of what they say is understood by people outside the family.
Sentences, not single words
Three and four word sentences are usual by now.
Mostly understood
A stranger should understand around three quarters of what your child says.
Questions appear
A three year old usually asks "what" and "where".
This page gives general information only. It is not a diagnosis. For your own child, see a registered speech-language therapist or a doctor.