In Turkish, two vowels generally do not appear consecutively without a consonant separating them. Buffer consonants (kaynaştırma ünsüzleri) are inserted to prevent this. The most common buffer consonant is 'y'.

Primary Uses of Buffer Consonant 'y':

The buffer consonant 'y' is primarily used when a noun ending in a vowel is followed by a case suffix that begins with a vowel.

1. With the Accusative Case Suffix (-ı, -i, -u, -ü):

If a noun ends in a vowel, and you add the accusative suffix:

• kedi (cat) + -i → kediyi (the cat)
• araba (car) + -ı → arabayı (the car)
• kapı (door) + -ı → kapıyı (the door)
• kutu (box) + -u → kutuyu (the box)
• ütü (iron) + -ü → ütüyü (the iron)

2. With the Dative Case Suffix (-a, -e):

If a noun ends in a vowel, and you add the dative suffix:

• anne (mother) + -e → anneye (to the mother)
• baba (father) + -a → babaya (to the father)
• kuzu (lamb) + -a → kuzuya (to the lamb)
• su (water) + -a → suya (to the water)

Other Important Buffer Consonants:

While 'y' is very common, be aware of other buffer consonants used in different situations:

• 'n': Often used with the Genitive case suffix (-ın, -in, -un, -ün) when the noun ends in a vowel.
  Example: araba + -ın → arabanın (of the car)
• 's': Typically used with the 3rd person possessive suffix (-ı, -i, -u, -ü) when the noun ends in a vowel.
  Example: araba + -ı → arabası (his/her/its car)

Understanding when and how to use buffer consonants is essential for correct word formation in Turkish.