The Stepped interpolation maintains the same keyframe value between keyframes. There is no slope between keyframes. For example, the curve in has four keyframes with a Stepped interpolation method.
With Classic Mode turned on, clicking the Stepped option in the FCurves window will make the Step and Step Next options appear.
Tangent options in Classic Mode A. Active Stepped option B. Step option C. Step Next option
When Classic Mode is turned off, the Step and Step Next options do not appear on the streamlined toolbar. These options can be accessed from the Dynamic Editor.
Tangent options in Updated Mode A. Active Stepped option
Step
When the Step option is active, the Stepped interpolation maintains the selected keyframe’s value until the next keyframe.
Step interpolation A. Selected keyframe B. Next keyframe
Step Next
When the Step Next option is active, the Stepped interpolation maintains the next keyframe’s value until the next keyframe.
Step Next interpolation A. Selected keyframe B. Next keyframe