Several of the Debian CD and Debian Live images are created using isohybrid technology, which means that they may be used in two different ways:
The most common way to copy an image to a USB flash drive is to use the dd command on a Linux machine:
dd if=<file> of=<device> bs=4M; sync
<file>is the name of the input image, e.g. netinst.iso
<device>is the device matching the USB flash drive, e.g. /dev/sda, /dev/sdb. Be careful to make sure you have the right device name, as this command is capable of writing over your hard disk just as easily if you get the wrong one!
bs=4Mtells dd to read/write in 4 megabyte chunks for better performance; the default is 512 bytes, which will be much slower
syncis to make sure that all the writes are flushed out before the command returns.