Quick answer
Й й is a consonant, not a vowel: the y in “boy” or “yes”. Its Russian name is и кра́ткое — “short i”.
Йй
Йй
y
чайtea
How to say it
Say “boy” and stop on the last sound. That glide is Й.
чайtea
майMay
музе́йmuseum
ру́сскийRussian
мойmy
трамва́йtram
Never alone
Й never starts a native Russian word and never stands as a syllable on its own. It always clings to a vowel: ай, ой, ей, ий.
Not the same as И
Мой and мои́ are different words. Treating Й as a plain и turns a one-syllable word into two — and changes the meaning.
Typical mistakes
Reading чай as “cha-i”
one syllable: “chay”
Й is a glide, not a vowel.
мой = “mo-i”
“moy”
Same rule.
Check yourself
Which word contains Й?
чай — tea.