What are these yellow lines in the action editor?

Can anyone tell me what these yellow lines are in my action editor? I have some armature bones set up, and keyframed (rot) at frames 1 and 11. For some reason, some of the bones are displaying yellow lines between the keyframes. It’s probably a basic question, but I’m fairly new at this…

It’s a visual aid that indicates no difference between the two keyframes for that channel (bone).

I see. What is happening is when I change the rotation of one bone, the position of another might be affected, but because I’m not directly moving that bone, it shows no change. Does that make sense?

Yes. As far as that bone knows, it is still where it was. The bars make it easier to see which bones you actually selected and moved when looking at a window full of dots.