Galaxy groups and clusters are vast assemblages of galaxies held together by gravity, representing the most densely packed regions of the universe’s large-scale structure. Galaxy groups tend to be smaller collections, typically containing up to around 50 galaxies, whereas galaxy clusters can host hundreds to thousands of galaxies. While there is no rigid boundary between the two, galaxy groups and clusters are often considered the building blocks of even larger cosmic structures known as superclusters, which are vast, loosely bound networks of galaxy groups and clusters that stretch across the universe. These gravitationally bound systems are crucial for understanding the distribution of matter in the cosmos and the evolution of galaxies over cosmic time.
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