Galactic rotation and dark matter

What is a galaxy's rotation curve? To which galaxies is it best applied, and what does it tell us about the distribution of dark matter? The plot rotation versus distance from the galactic center is called a galaxy’s rotation curve. In other words, it is the rotation curve for the milky way galaxy plots rotation against the distance from the galactic center. This is best applied to normal spiral galaxies like our own. This study tells us our Galaxy is very large and it also  provide the strongest evidence for dark matter.