inux outperforms NT in the category of reliability. The cost of the down times go to the administrators who must be there and the time lost to perform duties when the system is down. Very high regards go to the multitasking abilities and virtual memory usage that Linux provides. Although NT runs the same features, Linux provides the true meaning to running multiple programs without crashing the system. Although NT does support multiprocessing capabilities that just provides more terms for cost on hardware and doesn’t necessarily mean the system will run faster.In Unix-like systems, user-level activities are implemented by running processes. Most Unix systems support a ``thread'' as a separate concept; threads share memory inside a process, and the system scheduler actually schedules threads. Linux does this differently there is no essential difference between a thread and a process. Instead, in Linux, when a process creates another process it can choose what resources are shared (e.g., memory can be shared). The Linux kernel then performs optimizations to get thread-level speeds; see clone(2) for more information. It's worth noting that the Linux kernel developers tend to use the word ``task'', not ``thread'' or ``process'', but the external documentation tends to use the word process. When programming a multi-threaded application, it's usually better to use one of the standard thread libraries that hide these differences. Not only does this make threading more portable, but some libraries provide an additional level of indirection, by implementing more than one application-level thread as a single operating system thread; this can provide some improved performance on some systems for some applications. UNIX security is left very much up to the individual user. While System Administrators play the lead role in keeping unauthorized users off the systems, it is largely left to the individual user to secure their own accounts an...
