Dark matter is a hypothetical form of matter that appears to account for approximately 85% of the matter in the universe. It does not interact with electromagnetic radiation, making it invisible, but its existence is inferred from its gravitational effects on visible matter.
Laniakea is the galaxy supercluster that is home to the Milky Way and approximately 100,000 other nearby galaxies. It spans 520 million light-years and illustrates the large-scale structure of the universe.