All the seats in the coach compartment look the same, yet there are many different prices for those seats. Because of the fluctuations in passenger demand for travel, their perishable inventory, and relatively fixed seating capacity, carriers have adopted a variable pricing strategy. This strategy targets different market segments in order to control demand and maximise revenues. Underlying this strategy is the price-demand relationship. In module 2 we considered the demand side of the equation. Now we have the opportunity to look at pricing in more detail. What costs do carriers consider when determining ticket prices? In the first section we look at both carrier and customer costs and explain the difference between fixed and variable carrier costs. Why did I pay more for my ticket than the person sitting next to me? The second section revisits the foundation of the carriers' differential pricing strategy, the price-demand relationship. This helps us to better understand variable pricing and market segmentation, the role of fare rules, and the goals and processes of inventory, or revenue, management. How do carriers set prices? In the third section we outline various pricing strategies that carriers use when setting prices.