Arduinos reference voltage

I am right in thinking that the Arduinos reference voltage (aref?) can be used to set the sensitivity of the analog inputs? If so, how low can you go with this? I mean, what are the smallest voltage increments one can reliably measure?


Hi PlastBox,
A google search for arduino aref brings up this page explaining how to set aref for 1.1 volts or to an external reference.

the smallest increment is the reference voltage divided by 1024