FF, a segment is one flight number. If you go from Dallas to New York via Chicago, and the flight number remains the same, it is one segment. If it changes, it is two segments. As 2mm said, intercontinental flights don't count as any segments when counting for the max allowable for a continent. I will even confuse you a little more, since it is kind of fun. If you flew STO-SFO via ORD on the same flight number, it is considered your intercontinental. If you change flight numbers in ORD, it is an intercontinental and a segment.

Good luck...