Phonology is a branch of linguistics that studies sound systems in language. The term "phonology" comes from the Greek, namely "phone" which means sound and "logos" which means science or study. In this study, researchers studied how sounds are organized, recognized, and produced in different languages around the world.

The main aim of the study of phonology is to identify and analyze the differences in sounds in a language. Each language has a unique sound system, consisting of segmental sounds (such as consonants and vowels) and suprasegmental sounds (such as intonation, stress and syllable length).

In phonology, sounds in language are divided into phonemes and allophones. Phonemes are the basic sound units that differentiate meaning in a language. For example, in Indonesian, the sounds /p/ and /b/ are phonemes because they can change the meaning of words, such as "pat" and "bat". On the other hand, allophones are variations of sound that occur in a particular context. For example, the [p] sound in "pat" is pronounced slightly differently if it is at the beginning of a sentence, as in "Pat is my name."