Ease
What is ease when it relates to knitting?
Well, ease is the amount of extra 'room' built into a garment so that it fits and allows you to move in comfort. If I sewed a skirt to my exact measurements that skirt would fit, but it would prevent me from walking or sitting down without the skirt riding up.
Knitting fabric is stretchy therefore when you knit a hat you would knit it with negative ease, or smaller than the head measurements in order for the hat to fit and stay on the head.
Positive ease is when a garment is larger than the body measurements. A chunky, cabled sweater would flatter the figure if it was slightly larger than the body. This is a great article describing the differences between negative and positive ease.
P.S. Sorry about the lack of photos or charts.....
