Imagine a world without color. It’d be a bit hard to tell the difference between things. Imagine a world were one has trouble differentiating colors. Image a world were you can’t see the same colors as others. These are all real possibilities.
The ARIA spec has two levels of contrast ratios that text on a background should meet. The body text you are reading as you read is 7:1:1. A very high contrast ratio and meets the level three spec. Pretty dang good and pretty dang accessible.
We'll get into some of the attributes that can be added to your mark up (another chapter in your manual). In short, it's a specification that has been developed to standardized the way accessibility is handled by browsers and developers on the web. It gives us a way to 1) use native elements in the browser and have them work out of the box in the browser (if the browser supports ARIA.) and 2) allows developers to add these extra attributes to a site to extend the features that they are building to be accessible and be able to be parsed and understood through assistive technology.
There's also general rules and limits for color contrast, type sizes, and design best practices.
Whew! Glad we got that covered. Anyways, color contrast is a simple idea. If it’s hard to read for a user without an impairment, put yourself in someone else’s shoes. Yeah, light gray text on a white background softens the look and sometimes looks dope. BUT IT’S HARD TO READ, SILLY. At the end of the day, our job is disseminate information in the best way possible and engage
KNOW YOUR AUDIENCE. If you are designing for 55+: color contrast and legibility of colors on top of one another became a big freakin’ deal. If you are designing for a younger audience, it doesn’t matter as much, BUT still be mindful that anyone, at anytime, can access your designed content and should still be accessible to the greatest amount of people.