Microstep Mode Switching or just Mode Switching: Using AXISn_DRIVER_MICROSTEPS to set the micro-step mode used during tracking and AXISn_DRIVER_MICROSTEPS_GOTO to set the micro-step mode during gotos. Configuring both of these (as opposed to just AXISn_DRIVER_MICROSTEPS) allows potentially higher RPM's by reducing the required step frequency to within what the micro-controller is capable of (fewer step pulses for each rotation of the stepper motor shaft.)
Steps Per Degree: When tracking, the number of steps a motor axis takes to cover one degree of the sky.
StepStick: A widely used format in the 3D printer community for Stepper Motor drivers. They are small rectangular boards, with 8 pins on each side of the board. A variety of models are available with different current ratings and features.