Great news: You can���t get this one wrong. Either version of the word is correct.
Both are used across the English-speaking world, though in the United States and Canada, afterward is slightly more preferred while in the United Kingdom, Australia and elsewhere afterwards is used liked a bit more.
Because of this, some American language teachers tend to view afterwards as more formal ��� as the United States generally considers the Queen���s English more formal sounding ��� and recommend afterwards be used in academic or official works.
As a side note, afterward has a different meaning than afterword. The latter is an epilogue; you can remember the difference because ���word��� is used when referring to a part of a written book.
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