What are typical noise levels?

So my friend bought a couple premade Arduino boards and we started tinkering with them. Very, very cool stuff!

Anyway, without plugging anything into the boards we’re getting pretty high readings with analogIn(pin). I wouldn’t be surprised to get some noise, but we’re getting values ranging from ~550 to 700 on one board and ~400 to 600 on the other. Is this typical or am I missing something?

I’m quite new to physical computing so I may be missing something rather important.

Thanks.

It’s typical. If you measure a pin that’s not connected to anything, you can get completely random values - or just 0 all the time - you never know.