I dont understand deficits, Help?

I have no idea what a deficit is and how they contribute to weight loss. Can someone please explain this to be and tell me if im doing things right? Ill provide the info needed

eat less than you burn here's a couple of links

http://forum.bodybuilding.com/showthread.php?t=121703981&page=1

http://www.fitnessfrog.com/calculators.html

If you eat enough food to maintain all your body functions while you lie in bed & watch tv BUT you get out of bed & get active every movement you make burns calories. The difference between the number of calories you need to lie in bed & watch tv & the number of calories you burn when you are active is the defecit & this is the fat you lose.
Good luck

Actually, that's more a description of BMR (the lying in bed calories), and TDEE (total daily calories). A deficit is the number of calories you need to eat below your TDEE to lose weight effectively - 500 calories less a day for 1# weight loss a week, 250 for 1/2#. If your TDEE is, say, 2000 calories, you would eat 1500 a day to lose a pound a week - however, you don't want to eat below your BMR (which can slow down your metabolism and actually stall your weight loss). So, if your activity level is light and your BMR is 1600, you will lose weight a little more slowly, but a lot more healthily by eating the 1600. The trick with all this is picking the right activity level, and recalculate your BMR/TDEE as you lose weight or change your exercise/activity levels. There are lots of good calculators out there to figure your BMR (there's one on this site under the Tools tab) and TDEE,