조사 (josa) is the Korean word for postposition. Postpositions play very important roles in Korean and help determine a sentence’s meaning. They are also known as particles, suffixes or case markers.
A postposition is placed directly after the noun it’s modifying, without any space in between them. This is why they’re sometimes considered suffixes.
For example,
학교는 (haggyoneun) – The school (is)
Noun: 학교 – school
Postposition: 는 (neun) - subject marker
In Korean, it’s common for certain suffix-like attachments to vary based on the final letter or consonant/vowel of the syllable directly before it.
For example, the postposition 는 is used to mark the topic of the sentence, but only if the letter directly before it is a vowel. If it were a consonant, the postposition 은 (eun) is used instead. Both 는 and 은 mean the same thing and perform the same function in marking the subject of a sentence.
학교는 (haggyoneun) – The school (is)
Noun: 학교 – school
Final noun letter: Vowel ㅛ
선생님은 (seonsaengnim-eun) – The teacher (is)
Noun: 선생님 – teacher
Final noun letter: Consonant ㅁ
