When the world price of a good is lower than the domestic price, it creates a scenario where imports become necessary to meet consumer demand. In this situation, the domestic market experiences a shift in equilibrium due to international trade. The initial equilibrium price and quantity, denoted as \( P^* \) and \( Q^* \), are disrupted as consumers respond to the lower world price by increasing their demand, while domestic producers reduce their supply.

As a result, a shortage occurs, defined as the difference between the quantity demanded and the quantity supplied at the lower world price. This shortage is filled by imports, which are goods produced overseas and sold domestically. The volume of imports corresponds to the extent of the shortage, effectively bridging the gap between domestic supply and demand.

In terms of consumer and producer surplus, the introduction of imports significantly benefits consumers. The consumer surplus, which is the area above the price and below the demand curve, expands as consumers enjoy lower prices and increased quantities. This surplus can be represented as the sum of areas \( A + B + C + D \), where \( A \) is the original consumer surplus, and \( B, C, D \) represent the additional surplus gained from the lower price and increased quantity available through imports.

Conversely, producers experience a decline in their surplus, which is now limited to area \( E \) below the price and above the supply curve. They lose surplus areas \( B \) and part of their previous market share due to the influx of cheaper imports. Despite this loss, the total surplus in the market increases to \( A + B + C + D + E \), indicating that the overall economic welfare of the nation improves as the gains from trade outweigh the losses incurred by producers.

In conclusion, while consumers benefit from lower prices and greater availability of goods, producers face challenges due to increased competition from imports. However, the net effect of importing is a positive one for the economy as a whole, demonstrating that the gains to consumers surpass the losses to producers, leading to an overall enhancement in national welfare.