While every child's development is unique, there are certain articulation "norms" that are a useful way for parents to monitor their child's developmental progress.
These norms represent the typical age at which children develop particular speech sounds. As an example, development of the /g/ sound typically begins around two years of age, and may take up to age four to fully develop. This information is useful in determining if intervention is warranted for an individual child based on their age and the nature of speech errors they may be making. For instance, a child who cannot produce the /g/ sound at four years old may benefit from speech therapy.