Powering an Arduino Nano

I got a couple of these in the link below. I know I can power it via the usb, but can I power it via just 5v using a wire instead of the usb. On the bottom left and top left there are power pins not sure if these are just output or input as well.

Yes, you can connect 5V to the 5V pins (And GND to GND)

If you are using a very powerful power supply, a good recommendation is to use a fuse, which can protect your board in the event of a short circuit

rtek1000:
If you are using a very powerful power supply, a good recommendation is to use a fuse, which can protect your board in the event of a short circuit

As is so often pointed out here, it does not protect your board at all - a fuse protects the wiring from smoking and must be located at the power supply for that reason.