Some keys and keyboard combinations on your MacBook were born for Startup magic — either to get your Apple laptop booted up, help troubleshoot computer problems, or perform other technical tricks within El Capitan.

Key Effect on Your Mac
C Boots from the CD or DVD that’s loaded in your optical drive (if you have one) or a bootable USB flash drive
Media Eject Ejects the CD or DVD in your optical drive (if you have one)
Option Displays a system boot menu allowing you to choose the operating system and/or volume
Shift Runs your MacBook in Safe Mode, preventing your Login Items from running; runs a directory check
T Starts your laptop in FireWire or Thunderbolt Target Disk mode
Command+R Boots from the El Capitan Recovery HD
Command+Option+R Boots El Capitan Recovery using your Internet connection
Command+V Show OS X Console messages
Command+S Starts your MacBook in Single User Mode
Command+Option+P+R Resets Parameter RAM (PRAM)