1. Flat-panel door style. This is sometimes referred to as a slab-door style and is a signature element of modern kitchen design. You might see a modern kitchen using a Shaker door style, but that often falls into transitional rather than modern — which is not to say it can't be used; it's just not a purist's perspective.
3. Sleek and simple hardware. In modern kitchens you'll most often see C-channel hardware that's integrated into the cabinet, as well as tubular pulls or flat linear pulls. Lots of times the horizontal lines of the cabinets will be accentuated by cabinet hardware running the full length of the drawers and doors.
4. Lack of ornamentation. Always a signature of modern, this is often where contemporary and modern stop being similar. Whereas you might see patterned tile shapes or multiple materials with texture, color and patina in a contemporary kitchen, you won't see much of that in a modern kitchen. Flat-panel door styles and sleek hardware are joined here by a simple full-height glass backsplash and countertops without any pattern or veining.
5. Reliance on the beauty of natural materials. It's not to say that modern kitchens can't have a little bit of ornamentation, but when they do, they get it from the natural characteristics in a material, such as the horizontal grain of oak when it's rift cut or the natural beauty and veining of marble.
6. Emphasis on horizontal lines. You might not notice at first, but many modern kitchens share a tendency toward the horizontal: long, wide lines, stacks of drawer cabinets lined in a row, hardware set long and horizontal to accentuate the lines of the drawers. In this kitchen the floating panel of the back wall and the cutout accentuate the horizontal theme.