How power arduino nano without USB?

We can power some Arduino models with Battery, but some little Arduino devices (like pro mini,nano,mini)
How can we power them with Batteries?

(deleted)

How can we connect it to them?

At Uno it's the VIN pin, but check your boards specification.

@techiefellow

How does this relate to the original question from nearly 4 years ago? Maybe I missed it?