Unix and Unix like (such as Linux) operating systems are widely used in both servers and workstations. A Unix architecture is a computer operating system architecture that embodies the Unix philosophy. It may adhere to standards such as the Single UNIX Specification (SUS) or similar POSIX IEEE standard. No single published standard describes all Unix architecture computer operating systems.

There are many systems which are Unix-like in their architecture. Notable among these are the GNU/Linux distributions. The distinctions between Unix and Unix-like systems have been the subject of heated legal battles, and the holders of the UNIX brand, The Open Group, object to "Unix-like" and similar terms.
Some key features of the Unix architecture concept are:

• Unix systems utilize a centralized operating system kernel which manages system and process activities.
• All non-Kernel software is organized into separate, kernel-managed processes.
• Unix systems are preemptively multitasking: multiple processes can run at the same time, or within small time slices and nearly at the same time, and any process can be interrupted and moved out of execution by the kernel. This is known as thread management.
• Files are stored on disk in a hierarchical file system, with a single top location throughout the system (root, or "/"), with both files and directories, subdirectories, sub-subdirectories, and so on below it.
• With few exceptions, all devices and some types of communications between processes are managed and visible as files or pseudo-files within the file system hierarchy. This is known as everything's a file.