Keyframe interpolation

I have heard that in some other 3D software you can have different interpolation every keyframe and even on same keyframe's in and out. That sound just so wired and confusing. o_O
But in Blender if you change interpolate it will do it to all keyframes that's how you can't accidentally forgot wrong interpolation on to some keyframe. ^_^

But is someone really want to have different kind of in and out for the keyframe for some wierd reason. He can take change keyframe's Hanled Type to Vector and change it way he wants to every frame one by one.