Simple keyframe question in Blender animation I have a simple object (let's assume it is a cube), which can be rigged by a bone. I inserted 3 LocRotScale keyframes at t1 = 0s, t2 = 5s and t3= 10s, let's call them KF1, KF2 and KF3.

Between KF1 and KF2, I only move (pressing key G) the cube.
Between KF2 and KF3, I only rotate (pressing key R) the bone in the cube. 
With this setup, I expect the cube should start rotating only at time t2.
Strangely, when I play the animation, the bone/cube rotation ALREADY starts from time 0. What is wrong?
Your mistake was to animate the cube while you should have only used the bone. There were two different animations: the cube and the bone. If you choose to parent your cube to a bone (with ctrl P > Set Parent to > Bone), then use the bone only to control the cube. By the way, in the Dopesheet bottom menu, click on the arrow button, it allows to display only the keyframes of the selected object, it will help.