How do I install or upgrade Mac OS X 10.5 (Leopard) and earlier?

Note: To install or upgrade Mac OS X 10.7 (Lion), see How do I install or upgrade Mac OS X 10.7 (Lion)? To install or upgrade Mac OS X 10.6 (Snow Leopard), see How do I install or upgrade Mac OS X 10.6 (Snow Leopard)?

Before attempting to install or upgrade Mac OS X, verify that your computer meets the minimum system requirements. Then, continue your installation or upgrade:

1. Insert the install disc (or the first install disc if you have more than one) into your disc drive. Restart your computer while holding down the  c  key. This causes your computer to start up from the install disc rather than your hard drive. When you see the Happy Mac icon or the gray Apple insignia, release  c .
   
   
2. The Mac OS X installer should open automatically. Follow the on-screen prompts to read and accept the license agreement and begin the installation. When prompted to choose a destination disk, select your preferred location.
   
   
3. If you are installing or upgrading to earlier versions of Mac OS X, you can click Options... and select from the following options:
   • Upgrade Mac OS X: This option upgrades your current operating system to the new version, preserving all your files and settings.
     
     
   • Archive and Install: This option creates an archive of your current system files and installs a new copy of Mac OS X. You can also select Preserve Users and Network Settings, which imports all user accounts and network settings into the new system.
     
     
   • Erase and Install: This option completely erases the destination disk and then installs a new copy of Mac OS X. If you select this option, UITS recommends that from the pull-down menu next to "Format disk as:", you select Mac OS Extended or Mac OS Extended (Journaled).

   If you are installing Mac OS X for the first time, and not upgrading, your options are to Install Mac OS X or Erase and Install.

4. When the Mac OS X installation finishes with the disc, click Restart. Your computer will restart; if additional discs are required to complete the installation, the system will ask you to insert them. After the installation completes, a configuration program will begin automatically if you are installing for the first time, or if you are archiving and installing without preserving users and network settings. You will need to supply basic setup information for your computer.
   
   
5. Install any additional software you may have, and update your system software to ensure you have the most recent operating system components.