I don't know that there's a "correct" spelling, as it has a few different origins, namely Gaelic and Hebrew. I think of "Aidan" first, when I hear it said, but I went school with an "Adin" (his family is Jewish).
I don't think there is a "correct" spelling of the name. I've seen it spelled Aiden and Aidan. It's just preference I guess. I've also seen Ayden, but that was only once.
Re: What's the correct spelling of Aiden?
I think Aidan.
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