Every product on Amazon needs one or more product image. The primary image of your item is called the "MAIN." The MAIN image represents an item in search results and browse pages and is the first image customers see on a product detail page.
MAIN images must have a pure white background (pure white blends in with the Amazon search and item detail pages - RGB values of 255, 255, 255).
For more information and examples of good and bad product images, see Product Image Requirements and Preparing Product Images.
To fix a product image with a non-white background:
For Amazon image guidelines, see the category-specific style guides in seller Help.