Born outside Ireland
You are automatically an Irish citizen if one of your parents was an Irish citizen who was born in Ireland. You may then apply for your Irish passport.
You can become an Irish citizen if one of your grandparents was born in Ireland, or you can become an Irish citizen if one of your parents was an Irish citizen at the time of your birth, but was not born in Ireland. If you're eligible, you can register your birth on the Foreign Births Register. This is a separate application and must be completed before you can apply for your passport.