It's a tool that brings attention and understanding to how color contrast can affect different people with visual impairments.
The Web Content Accessibility Guidelines (WCAG) covers a wide range of recommendations for making Web content more accessible. Just a tiny part of making the web more accessible is accommodating for those with a form of blindness or low vision.
The standard grading system is a great start, but I thought I'd try to humanize the people who are affected by the different grades.
“Precision colors for machines and people.”
“Solarized is a sixteen color palette (eight monotones, eight accent colors) designed for use with terminal and gui applications. It has several unique properties. I designed this colorscheme with both precise CIELAB lightness relationships and a refined set of hues based on fixed color wheel relationships. It has been tested extensively in real world use on color calibrated displays (as well as uncalibrated/intentionally miscalibrated displays) and in a variety of lighting conditions.”
CSS-Tricks: Color Rendering Difference: Firefox vs. Safari
"The purpose of these color profiles is something I could into another time, but the important thing to remember to avoid problems like Norm's is to make sure all your images were exported in the same way and so they either don't have a color profile or all have the same color profile. This will ensure that the site, at least color-wise, renders the same from browser to browser."