XOXO may refer to any of the following:
1. Short for eXtensible Open XHTML Outlines, XOXO is a format for processing by XML engines, where the outline is a hierarchical, ordered list of elements.
2. Short for hugs and kisses, XOXO is a way of letting someone know you care. Both the X and the O can be thought of as a hug and kiss, therefore it is acceptable to say the X is a hug and the O is a kiss, or vice versa.