If dark matter is 'invisible,' how do we know it exists?

dark matter map showing magenta fuzzy sections in the center and to the sides of the sky map with a bright arc flowing the through the middle of the sky map.

In April 2023, scientists from the Atacama Cosmology Telescope (ACT) collaboration created a map of the universe showing the detailed distribution of dark matter, a mysterious form of matter that makes up around 85% of the total matter in the universe. 

While creating any accurate map of matter distribution across the cosmos is an impressive feat, it is particularly extraordinary for dark matter, which does not interact with light and thus cannot be seen directly with telescopes or other instruments.