How to make Ubuntu Linux boot to text mode?

My Ubuntu boots to GUI mode by default. How to make Ubuntu Linux boot to text mode?

If you are using Ubuntu older than 16 such as Ubuntu 14.04:

1. Edit /etc/default/grub
   Change GRUB_CMDLINE_LINUX=... to GRUB_CMDLINE_LINUX="text".
   

2. Backup your old grub config
   `$ sudo cp -n /etc/default/grub /etc/default/grub.bak-date +%s `
   

3. Update grub
   $ sudo update-grub
   

If you are using Ubuntu 16.04 which uses systemd, please follow this tutorial:

How to Change Systemd Boot Target on Linux