Each virtual or dedicated server has its own Operating System and works independently from the hosting machines of other clients. Updating the OS is frequently overlooked, but doing that might have a wide range of benefits for your sites. The most significant reason to use the most recent version is that patches are usually released to deal with security holes inside the Os code, so if you don't install the updates, you risk individuals with harmful intentions to use these holes and to get access to your content. Operating system updates are also released for enhanced performance of the system in general and for better compatibility with the hardware available on the market, which could immediately affect the efficiency of your sites. If the efficiency and the security of your scripts is the reason to update them, you may also discover that their most up-to-date versions require an updated Operating System in order to function effectively, consequently keeping the OS up-to-date is always a good idea.