Phonological Development is characterized by certain processes that are created to simplify the articulatory movements for a word and are suppressed by a certain age.
As children develop, they progress through the prelinguistic stages, first 50 words stage and continue progressing throughout childhood.
(Bauman-Waengler, 2020)
The following is a chart depicting typical phonology development from the Speech and Language Development Chart (Gard et al., 2010)
(Gard et al., 2010)