Right, on to this old chestnut. If you are talking about your evening meal, usually after you get home from school or work, do you say dinner or do you call it supper?
Where I come from (UK; near London) almost no one says supper, they call it dinner. Supper is usually the snack you eat just before going to bed (I remember my mum saying to me as a kid "Time for supper, then up to bed").
When I teach here in China though, almost everyone calls it supper. One child told me today "My teacher said 'dinner' is what you eat at a restaurant, and 'supper' is what you eat at home"
As far as I'm concerned (and my teaching here), whether you call it dinner or supper is down to personal preference; i.e. whatever you were taught as a kid. No one ever sat me down and told me any rules concerned with the naming of meals!!
Actually, when I was a nipper (small child), I seem to remember two different naming conventions thus:
Breakfast > Lunch > Dinner
Breakfast > Dinner > Tea
Both of those systems used supper as a name for the pre-bedtime snack.