>>58039Aircraft need to land and takeoff into the wind as much as possible. The runway(s) best aligned with the prevailing wind is usually the active runway(s) at any point in time.
For example having a north-south and east-west runway means any conceivable wind direction would be less then 45 degrees from the active runway.
Aircraft join a traffic circuit around the active runway.
You can have up to three parallel runways. The left and right are used for left-hand and right-hand circuits respectively while the center runway is restricted to straight-in approaches only. These sort of airports are complex and hence require towers and radar..