The curve is the market's price of time. Its slope is set by cost-of-carry against convenience-yield, and its shape gets names: upward sloping is contango, downward sloping is backwardation, and real curves often do both at once.
Traders read the curve for positioning as much as for price: a front-end kink that steepens while the back stays flat is a supply story, not a demand story.
Example: a natural gas curve might show $2.90 for October, $3.40 for January, $3.00 for April and $3.10 the following January — winter humps repeating every year, the signature of seasonality.
Related: contango, backwardation, cost-of-carry, convenience-yield