By age
Speech at two years
Two years is the age at which most families first notice a gap, because other children at the playground are putting words together.
Two-word phrases
Many children join two words by this age. "More milk" counts.
Half understood
A stranger understands roughly half of what a two year old says. Less than that is worth a check.
Frustration is a signal
A child who cannot ask often shows it in behaviour instead.
This page gives general information only. It is not a diagnosis. For your own child, see a registered speech-language therapist or a doctor.