Where is the GUID Partition Table stored on a device?

view story

http://unix.stackexchange.com – A friend of mine used my USB stick to install a new version of OS X on his mac. Now that I got it back, I wanted to wipe it (I use Linux myself). However, I'm having a bit of trouble doing so. The first thing I did was write a Fedora LiveCD to it, using dd: # dd if=Fedora.iso of=/dev/sdb This, I thought, would overwrite the partition table which lies at the beginning of the device and consequently delete the partitions the OS X installer had created. However, I was wrong, the partitions were still there. So I looked up GUID partition tables and realized they add headers not only at the begi (HowTos)