Demand is the consumer's willingness and ability to purchase goods and services at a given price, while also considering the law of demand which states that the quantity demanded of a product or service is inversely related to its price. This means that as the price increases, the quantity demanded decreases, and vice versa. However, modern theories have expanded on this concept, taking into account various factors such as consumer preferences and income levels. Demand is a fundamental concept in economics and can be influenced by supply, which is the availability of goods and services in the market. It is also affected by the consumer's desire, ability, and willingness to pay a certain price for a product or service at a given time. Ultimately, demand plays a crucial role in shaping the market and determining business strategies.