What is a Headshell and what does it do ?

It adds some weight to the Arm for better tracking

Ok , if you trade out headshells with cartridges mounted in them , is there a new set up procedure required ? Or do you just remove one , install another and play records ?

Thank you

Except in the unlikely event that the two cartridges need the same VTF, antiskate and arm height settings, those will have to be adusted with each cartridge change.

Additionally, much depends on how accurately the headshell/tonearm connection was machined. If it puts the cartridge in *exactly* the same position each time its removed and replaced, great. Of course no mechnical interface is perfect. To whatever degree there's room for variation, you would need to re-check overhang, zenith angle and azimuth.

If you plan to have 2 different cartridges with same VTA and VTF when mounted, than you just swap'm. If you plan to use another cartridge let's say for 78rpm records, regardless of VTA and VTF it probably wouldn't matter

At a minimum, you're generally going to have to adjust vertical tracking force for each cartridge, and usually anti-skating as well. Most cartridge have their own individual sweet spot within the recommende tracking force range.

Not mentioned up to this point, but it's waaaay easier to mount a cartridge on a detachable headshell AND significantly lower the risk of damaging the cantilever during the process.