Fcurve Modifiers Made Easy

After animating some property in Blender using keyframes you can edit their corresponding curves. When something is “animated”, it changes over time. This curve is shown as something called an F-curve. Basically what an F-curve does is an interpolation between two animated properties. In Blender, animating an object means changing one of its properties, such as the object’s location, or its scale.

the scene above  animated using quick easy animate or quake easy animate, you want

As mentioned, Blender’s fundamental unit of time is the “frame”, which usually lasts just a fraction of a second, depending on the frame rate of the scene. As animation is composed of incremental changes spanning multiple frames, usually these properties are not manually modified frame-by-frame, because:

• It would take ages!
• It would be very difficult to get smooth variations of the property (unless you compute mathematical functions and type a precise value for each frame, which would be crazy).

This is why nearly all direct animation is done using interpolation. (from blender)