A Binding connects an Input Action to a physical control.

Example:

Jump
├── <Keyboard>/space
└── <Gamepad>/buttonSouth

For WASD movement, use a 2D Vector Composite:

Move
└── 2D Vector
    ├── Up: W
    ├── Down: S
    ├── Left: A
    └── Right: D

Read the same action regardless of device:

Vector2 movement =
    moveAction.action.ReadValue<Vector2>();