Le hertz (symbole : Hz) est l’unité dérivée de fréquence du système international (SI). Un hertz est équivalent à un événement par seconde (s ou ).

GHZ or GHz may refer to:

• Gigahertz (GHz), a unit of frequency
• Greenberger–Horne–Zeilinger state, a quantum entanglement of three particles.
• Galactic Habitable Zone, the region of a galaxy that is favorable to the formation of life
• Green Hill Zone, the first level in Sonic the Hedgehog (1991 video game)

The hertz (symbol Hz) is the unit of frequency in the International System of Units (SI) and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide conclusive proof of the existence of electromagnetic waves.