This chapter addresses how to decode the instantaneous hand position from a population of motor cortical neurons recorded from a macaque monkey. It also defines how information about how the hand position changes over time can be used to improve the decoding. It also examines how neurons in the motor cortex carry information about upcoming movements. This information can be used to decode the direction of a movement made to one of eight targets. The chapter discusses the linear filter approach. The advantage of this approach is that one can easily add more neurons or more kinematics to the model. The linear filter can be used on data recorded outside the motor cortex. The main advantage of this approach is that it is very fast and it is easy to calculate.