Aref???

what is that???

maybe few more words can help to understand your question… anyway, straight from ATMEGA datasheet, page 4 (pin description):

1.1.8 AREF
AREF is the analog reference pin for the A/D Converter.

i am new to electronics, so whats a

A/D convertor.

?

i am new to electronics,

Are you new to computers or can’t you use Google?

An A/D convertor is an Analog to Digital convertor. It takes in an analog, variable voltage and outputs a digital, numeric result. A digital voltmeter is a kind of A/D convertor.

^Thanks =D