Reasons for having def and FK bones?

I have recently been rigging a character model and have been through some great tutorials but two of the main ones I zoned in on have one difference. One uses a whole set of bones seperate that are the blah_def (for deform only)…and then IK and FK while the other video just uses def and FK as one…Could someone tell me if having a separate set of bones for deform is worth doing or could i just deform to FK bones?

Sure you can just use one set of bones. the purpose of having different sets are just for advanced rigging techniques, like IK/FK blending, squash and stretch; things like that.

Little bit more effort on rigging = easier better looking animations later

gotchya

I use the Deform bones as my FK bones as well, I see no sense in separate bones for that. I think the idea behind separate FK & deform bones is so if you a deform problem, you know which bones to look at & refine weight painting on. Since my FK bones deform the mesh, I know which bones to look at when problems occur, the FK bones. Then where I have IK bones, I make separate bones for that, with the deform option disabled. Then when the rig is switched to IK, the FK/deform bones copy the rot of the IK bones.

Randy