Mac operating system from disc at startup Hello everyone and thank you in advance.

I have just downloaded Linux Ubuntu and put it on a disk. What i want to do is to hold C during the Mac startup so that I can choose to boot my mac through the CD with the Linux Ubuntu operating system. However, I am worried about what will happen when I run my Mac through this CD and I have some questions


How do I change back between operating systems?
Will the startup commands work the same?
What will happen if I turn my computer off and eject the disk? Will
my Mac just launch normally?
Any other information about booting from a disk that may be relevant


I understand this might seem stupid but please answer if you have any idea of how this whole "boot through CD thing works"! Thank you
Just press Alt/Optn on startup.
Absolutely
Yes
There is noting special, read here on other bootup options