A gyroscope measures angular velocity (the rate of change in orientation angle), not angular orientation itself
Must first initialize the sensor position with a known value (possibly from the accelerometer), then measure the angular velocity (ω) around the X, Y and Z axes at measured intervals (Δt)
ω × Δt = change in angle
The new orientation angle is the original angle plus this change
This is integrating - adding up many small computed intervals - to find orientation
Repeatedly adding up increments of ω × Δt results in small systematic errors becoming magnified over time
Gyroscopic drift---over long timescales the gyroscope data will become increasingly inaccurate