Uno power via momentary button

Hi,

I have a Uno (Bluno Nano) project, controlling led strips with a 5V power source.

I’d like to use a momentary button to turn power on/off. Wondering what the best way would be to achieve this? Is there a sparkfun component I could use?

Why does it have to be a momentary button? What would be the problem if you used a push on - push off?