Is it recommended to use a capacitor between Vin and GND on Arduino nano?

I want to power the nano on Vin pin. Should I use a buffer capacitor? (I think it is called that.)

Yes, it is recommended to use a filter cap.
It wouldn't hurt to add one across the 5V line as well .

What value? And why do I need one on the 5V pin?

What value? And why do I need one on the 5V pin?

Why do you need one on the Vin ?

Vin and 5V on the Nano already have 47uF caps on them.
If the wires from your supply to the Vin pin are long, extra capacitance on Vin can't hurt.

raschemmel:
Why do you need one on the Vin ?

Because that is where the Arduino gets the power from.

Because that is where the Arduino gets the power from.

It's because if you add filtering on the raw dc input , it makes the regulated dc output more stable because the input voltage is more stable. Ideally, you filter it twice. on the raw input and the regulated output.