The derivation of an individual demand curve explains how the quantity of a product a single consumer wants changes as the price of that product changes, while keeping all other factors like income and tastes the same.

To derive this curve, follow these steps:

1. Start with a budget line and an indifference curve map.
2. Find the point where the budget line touches the highest possible indifference curve; this is the consumer equilibrium.
3. This point creates one price-quantity combination.
4. Adjust the price of the good to rotate the budget line.
5. Find the new optimal equilibrium point.
6. Plot these points on a new graph and connect them to draw the individual demand curve.

Key Properties:

• The curve usually slopes downward because of the substitution effect (the good becomes cheaper compared to others) and the income effect (the consumer feels richer when prices drop, for normal goods).

Main Assumptions:

• Consumers try to get the most utility (satisfaction) possible.
• Consumers act rationally.
• Income, tastes, and the prices of other goods remain fixed.