Demand is the willingness of a consumer to buy a good or service
The law of demand refers that when the price of the good/service is high is demand of the item is low but when the price is low the demand is high
When the price is low the quantity high but when the price is high the quantity is low
Income , price , taste , quantity are one of the most important determinants of demand
Movement in demand refers how the demand of the good or service functions but the change in demand curve is a change by the sellers
A contraction in demand defines a descrease in the quantity demanded while a extension defines to the increase in quantity demanded
when shop keepers dont buy in quantity from the retail it because the price of the quantity has increased , a fall in demand refers to the quality , taste or the price difference , its about a single item
Supply
Supply is the willingnees and want for private companies and firms to provide goods and services in different price levels. Firms mostly want to supply goods or service in high prices , the higher the price the higher the supply is.
Relation between supply and price
Firms which are retiring soon can earn higher profits if they supply more
New firms can be intrested if higher price of supply can cover there production cost