What is ESD, ESD protection equipment, ESD protection diode circuit, ESD reverse

 ESD5Z Series 5 V 105 pF 3.3 Vrwm TVS and ESD Protection Diodes - SOD-523

https://www.futureelectronics.com/p/electromechanical--circuit-protection--esd-protection/esd5z3-3t1g-onsemi-8196941