about data size

hi,
i have a doubt.
after compiling the program the bottom of the page shows
data=9.0 xdata=0 warings =0 like this.

what is this data and xdata
i think data means how many bytes allocated to variables in the program in the form of bytes .
but iam not declaring any variables through out the program the data label shows always 9.0 bytes
what is this can u explain ?