dd is a command-line utility for Unix and Unix-like operating systems whose primary purpose is to convert and copy files.[1]


dd is also used to make a usb flash drive bootable using an image (.iso, etc).

To make the usb stick usable again you must recreate the partition using a Master Boot Record, can be easily achieved with Disk Utility:

Now the usb stick will be detected/usable on any machine (Windwos/Unix).