JJ Thompson's cathode ray experiment is accredited with the discovery of the electron. Cathode ray tubes (CRTs) were once used to display images on old televisions. There is a cathode (negatively charged) and anode (positively charged) at the opposite ends of the interior of the tube.
JJ Thompson ran electricity through the CRT. Being negatively charged, the electrons were attracted towards the positively charged end of the tube. A small hole was punctured at this end, which allowed some of the electrons to pass through. This beam of electrons hit a phosphate-coated backboard that glowed upon being struck by the electrons. In this way, Thompson could designate where the electrons were striking.
At the time of the experiment, the term "electron" was yet to be implemented. Therefore, it was called the "cathode ray experiment".