What are the different power modes and when should I use them?

There are three power modes: Eco mode for maximum run time during longer cleans, Auto/Med mode for an optimum balance of power and run time with suction that automatically adapts to dust levels, and Boost mode for intensive spot cleaning of ground-in dirt. To get the best performance and battery life, Dyson recommends using Eco or Auto/Med mode. (Pages 3, 14)