Appendix B. Update to Safari 4

Updating from Safari 3 to Safari 4 is a cinch, but you can't use Safari 4 unless you also have the correct version of Tiger (Mac OS X 10.4.x) or Leopard (Mac OS X 10.5.x). The Mac's built-in Software Update feature can take care of everything for you.

Automatic software updating is controlled by the Software Update preference pane, where you can set how often the Mac checks for updates and whether downloading them happens automatically or waits for your approval. So, depending on your settings, your Mac may have already guided you through the download, and even the installation, of your required system updates and Safari 4.