These two images were taken in the same position several minutes apart. The first image was taken at ISO 12800, F3.5, 1/25th. The second image was taken at ISO 100, F8, 2.5 seconds. The light had increase by 3 stops of light between the images, that is why the exposures aren't absolutely perfect compared to the Exposure Triangle, but the same principles applied.
The image quality dramatically increased when the ISO was reduced to 100.