Scarcity exists because resources are limited while human wants are unlimited. Scarcity means not all goals can be pursued at the same time, requiring trade-offs. Scarcity is determined by production costs rather than importance - air is more important than diamonds but diamonds are scarcer since they have higher production costs to find and process them. Evidence of scarcity includes the record high copper prices from increased demand and constrained supply, leading some to steal copper due to its growing scarcity.