: Open Terminal and paste the following command to create the installer: sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Yosemite.app Safety & Updates
: Open the "Install OS X Yosemite" app from your Applications folder to begin the upgrade process. Creating a Bootable USB (Recommended) yosemite 10.10 download dmg
Most people want a DMG because they want to wipe a hard drive and install fresh. Since the App Store gives you an .app , you need to convert it to a bootable USB drive. : Open Terminal and paste the following command