Choose the USB stick and press <b>Enter</b>. The USB stick appears as an external hard disk and might be labeled <b>EFI Boot</b> or <b>Windows</b> like in the following screenshot:
[[!img install/inc/screenshots/mac_startup_usb.png class="screenshot" alt="Screen with the logo of an internal hard disk labeled 'Macintosh HD' and an external hard disk labelled 'Windows' (selected)"]]
[[!img install/inc/screenshots/grub.png class="screenshot" alt="Black screen ('GNU GRUB') with Tails logo and 3 options: 'Tails' and 'Tails (Troubleshooting Mode)' and 'Tails (External Hard Disk)'."]]
The <b>Troubleshooting Mode</b> entry disables some features of the Linux kernel and might work better on some computers. You can try this option if you think you are experiencing hardware compatibility errors while starting Tails.
The <b>External Hard Disk</b> entry makes it possible to [[start from an external hard disk|doc/advanced_topics/external_hard_disk]] and some [[problematic USB sticks|support/known_issues#problematic-usb-stick]].