Last week Apple released a security update to address the Digi Notar root certificate vulnerability, but in doing so revealed that the company may no longer support Power PC-based Macs, at least when it comes to security updates.
Unlike previous security updates that have supported Leopard and even Tiger, Apple's latest update requires OS X 10.6 and OS X 10.7, and this means that users running OS X 10.5 will not be able to update their systems.
There are also tweaks to Face Time (you can snap live photos), Notes (tables and pinning), and Spotlight (improved search), along with dozens of other tiny changes and tweaks.
Additional information on mac OS High Sierra can be found in our mac OS High Sierra roundup, which includes details on all of the new features found in the update.
The current version of the software is 4.0.5 and its last update happened on 8/09/2011.
As with i OS, Siri has gotten smarter with cross-device syncing.
If you have an early Intel-based Mac that is running Tiger or Leopard, then the only way to ensure you can update it is to upgrade your system at least to Snow Leopard.
This requirement for having at least Snow Leopard means that any Mac user running a Power PC system, be it a G4 or a G5, will not be able to run the latest security update.
Without an official security update, addressing security vulnerabilities that are found may be a bit of a challenge, if possible at all.
Most of the time security problems lie in the programming of specific services on the system, so unless you can manually alter a setting or two to perform the same actions as the security update, then the only option is to limit the use of the affected services on your system.