Are your parents Irish citizens?
If either of your parents was born in Ireland, and is an Irish citizen, you are automatically an Irish citizen – wherever you were born. You can Follow this link to apply for an Irish passport – although having a passport is not a necessary to being an Irish citizen.
However, if either parent is an Irish citizen but born outside Ireland, it is a little more complicated. You are not automatically an Irish citizen – but you may be entitled to become one.