Demand pull inflation can be described as persistent rise in prices due to increase in expenditure. It occurs when the demand for goods and services in an economy exceeds its supply, causing the prices of those goods and services to increase. As demand increases, producers are forced to increase their prices in order to maximize profits, and consumers continue to pay higher prices as long as their demand for the goods or services remains high. This cycle can continue until the economy reaches a point where the supply of goods and services can no longer keep up with demand, at which point inflation may become unsustainable.