Animation Graph
An animation graph is an asset which applies some logic to animations. While it is running, the animation graph outputs a pose at each frame. Animation graphs run automatically at the start of each session.
To have control over animation transitions you will have to create a state machine in your animation graph.
While it is running, the animation graph is either in a state or in a transition between states. If it is in a state it computes and outputs the pose of that state. If it is in a transition between states, it blends between the pose of the initial state and the pose of the next state to generate the final pose.