What is a pulsar and what do they emit every time they rotate?

A pulsar is a highly magnetized, rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. As it spins, these beams sweep across space like a lighthouse, and if one of the beams points toward Earth, it can be detected as regular pulses of radiation, typically in the radio wavelengths. This pulsing occurs at highly regular intervals, making pulsars valuable for astronomical studies and tests of fundamental physics.