Millisecond pulsars spin at an exceptionally fast rate. With a rotation rate of more than 40 revolutions per second and a pulse period of fewer than 25 milliseconds, millisecond pulsars typically indicate a younger pulsar. Their pulses are extremely even and very regular, making them easy to identify and use as standards for calculations.
This slower pulsar is the most common type seen, typically having a rotation of about once per second. Once the rotation rate of a millisecond pulsar slows down, it becomes more unpredictable and less easy to identify. The rotation eventually will slow down to the once-per-second rate of an ordinary pulsar.
This sub-type includes two pulsars orbiting around each other. Binary pulsars can sometimes orbit around larger stars, and can be difficult to identify.