Whether you’re in a boot emergency or you need to repair your Mac’s hard drive, it’s easy to create a Mac OS X Lion (10.7) USB install drive. You can use a flash drive (8GB or larger) to install Lion to a freshly formatted hard drive, and in this guide, we’ll show you how.

This process consists of a few steps. First, make sure your USB drive is formatted for use with a Mac, then download the OS X Lion installer from the App Store and copy it to your flash drive. Finally, use your bootable flash drive to install Lion on your Mac.

Not all USB drives can be used with a Mac out of the box. If your USB drive does not specifically say that it is compatible with Mac, you will need to erase and format your drive for use with a Mac. Here’s how:

Insert the USB stick into the USB port on your Mac.