What is law or theory of demand state?

The law or theory of demand states as consumers we derive satisfaction or ‘utility’ like a result of consuming a good or a service. It varies by consumer to consumer; you may obviously have no utility yourself at all when you consumed a specific good or service wherein case you would not be a potential buyer. This theory states that as prices reduces, the utility or satisfaction increases for the consumer as other substitute goods or services would turn into relatively more costly, thus consumption would rise as price decreases and vice versa. When price falls that attracts more consumers in the market additionally as causing existing consumers to buy more, since the good or service is currently cheaper. The marginal utility is the additional utility gained through the consumer, through the consumption of one more unit; this is normally expected to fall while consumption rises and vice versa.