When I first became an apprentice, I knew next to nothing. Now, I can tell you all different kinds of things. Like how tool presetters are devices on lathes that are used to quickly and efficiently determine tool geometry offsets on the X and Z axis. You see, the tool tip makes contact on the surface of the a probe that constant records the turret position in the offset screen.
I could also tell you how a toolholder is used for the sake of rigidly holding a cutting insert in place during machining. In our industry, we use toolholders not for tool storage, but instead to secure a tool in a CNC machining device to maintain accurate standards of tooling.