General Question Input/Pulldown?

Projects General Guidance
1

Hi,

i just started to play around with an Arduino Uno.
I have a digital pin as an input. When i just attach a wire to the pin the pin-status becomes high, and stays. There is only the wire hanging in the air...

So i assume that i must use an external pulldown-resistor on any (digital)input, is that right?

2

Or, cheaper still, use the built-in pullups.

3

And than use the switches to switch to gnd?

thanks! :wink: