How many galaxies does a true galaxy cluster typically host?

Hundreds or even thousands of individual galaxies

There is a significant distinction in scale between galaxy groups and true galaxy clusters. A galaxy group, while itself containing multiple galaxies, is relatively modest. In contrast, a true galaxy cluster represents the massive end of the spectrum of gravitationally bound structures. These gargantuan systems are defined by their membership, hosting hundreds or even thousands of individual galaxies. These galaxies are all bound together by a shared, colossal gravitational field, spanning volumes that can extend over several million light-years across, making them structures of the largest known scale in the universe.