Color contrast is the relationship between two colors. In terms of accessibility, it is a small change that can make a big impact. We want the color contrast behind the background and foreground to have a contrast ratio of 4.5:1 in order to meet the Level AA, WCAG 2.1. WCAG is Web Content Accessibility Guidelines.
There is a free Colour Contrast Analyzer tool that you can download and use to check your color contrast. Review the video to learn how to use the tool.