Live USB 是USB随身碟或USB硬盘，里面含有完整的操作系统，可以被用来开机（booting）。Live USB很像live CD，但基本上有能力更改设置，而且可以把软件安装回USB设备上。像live CD一样，live USB可以使用在嵌入式系统系统管理（embedded systems system administration），数据还原（data recovery），或是不需要把操作系统安装到主机硬盘（local hard disk drive）里的测试。许多操作系统，包含微软的Windows XP Embedded和许多Linux套件和BSD可以被安装在随身碟上使用。

A live USB is a USB flash drive or a USB external hard disk drive which contains a full operating system that can be booted. Live USBs are closely related to live CDs, but can sometimes persistently save settings, and can permanently install software packages back onto the USB device. Like live CDs, live USBs can be used in embedded systems for