sudo dd if=/dev/sdb1 of="disk-image"

sudo dd if=/dev/sdb1 of="disk-image"

can anyone explain roughly to me is it this code do some recovery from /dev/sdb then output it to "disk-image" ? But then how can i access the "disk-image"? it cannot be read , and it told me its a binary file...

http://wiki.linuxquestions.org/wiki/Dd

thanks