Objects Appear Colored if they Reflect Some Wavelengths of Light Better than Others

When light falls on an object, some is absorbed. The light that isn't absorbed is reflected off the object's surface; this is the light we see. The object on the left of this diagram absorbs shorter (blue and green) wavelengths better than long (red) wavelengths and therefore appears red. The object on the right, which looks green, absorbs red and blue better than green.