Understanding the concept of demand:
Demand refers to the willingness and ability of consumers to purchase a particular product or service at a given price and time. It is an essential concept in economics as it drives the production and distribution of goods and services in a market economy.

Distinguishing between wants and demands:
Wants and demands are often used interchangeably, but they have distinct meanings in economics. A want is a desire or a need for a particular product or service, which may or may not be backed by the ability to purchase. On the other hand, demand occurs when a want is supported by the ability and willingness to pay for the desired product or service.

Explaining the factors that turn a want into a demand:
To understand why a want becomes a demand only when it is backed by the ability to purchase, we need to consider the following factors:

1. Ability to purchase:
The ability to purchase refers to having sufficient financial resources to buy the desired product or service. Without the necessary purchasing power, a want remains unfulfilled and does not translate into demand. For example, a person may want to own a luxury car, but if they do not have the financial means to afford it, the want does not become a demand.

2. Necessity to buy:
While wants are driven by desires, demands are often influenced by necessity. A want becomes a demand when there is a perceived need or requirement to purchase the desired product or service. For instance, a person may want to buy a new laptop, but it only becomes a demand when their old laptop becomes obsolete or no longer meets their needs.

3. Desire to buy:
Though desires play a role in wants and demands, the desire to buy alone does not necessarily turn a want into a demand. Demand requires more than a mere wish or inclination to buy; it necessitates the intention and willingness to take action and make a purchase.

4. Utility of the product:
The utility or usefulness of a product or service is another crucial factor that transforms a want into a demand. If a particular product is perceived as valuable and capable of satisfying the consumer's needs or wants, it is more likely to generate demand. The utility of a product influences the consumer's willingness to pay for it, thereby converting a want into a demand.

Conclusion:
In conclusion, a want becomes a demand only when it is backed by the ability to purchase. While desires, necessity, and utility are important factors, the presence of financial resources and willingness to pay are essential to convert a want into a demand. The concept of demand is vital in understanding consumer behavior and shaping the dynamics of the market economy.