Usually digital illustrators use blends to achieve gradient effects in their artwork (Select objects then Object>Blend>Make). Please don't confuse blends with gradients, they are two different things. Think of blends as gradations between multiple vector objects. In Adobe Illustrator the blends are actually live transitions between objects that will automatically update when you distort or change the position of one of the blended objects. The automatical number of those transition steps is based upon the difference in shape and color between the the original objects. (see the examples below)To access the steps as individual objects the blend has be expanded (Object>Expand), but after it will no longer be live. A manual way to control number of transition steps is if you access the the blend options dialogue box (Object>Blend>Blend Options>Spacing>Specific Steps).
difference in shape