NetWare is a discontinued computer network operating system developed by Novell, Inc. It initially used cooperative multitasking to run various services on a personal computer, using the IPX network protocol. The final update release was version 6.5SP8 in May 2009, and it has since been replaced by Open Enterprise Server.

The original NetWare product in 1983 supported clients running both CP/M and MS-DOS, ran over a proprietary star network topology and was based on a Novell-built file server using the Motorola 68000 processor. The company soon moved away from building its own hardware, and NetWare became hardware-independent, running on any suitable Intel-based IBM PC compatible system, and able to utilize a wide range of network cards. From the beginning NetWare implemented a number of features inspired by mainframe and minicomputer systems that were not available in its competitors' products.

In 1991, Novell introduced cheaper peer-to-peer networking products for DOS and Windows, unrelated to their server-centric NetWare. These are NetWare Lite 1.0 (NWL), and later Personal NetWare 1.0 (PNW) in 1993. In 1993, the main NetWare product line took a dramatic turn when version 4 introduced NetWare Directory Services (NDS, later in February 2004 renamed eDirectory), a global directory service based on ISO X.500 concepts (six years later, Microsoft released Active Directory). The directory service, along with a new e-mail system (GroupWise), application configuration suite (ZENworks), and security product (BorderManager) were all targeted at the needs of large enterprises.

By 2000, however, Microsoft was taking more of Novell's customer base and Novell increasingly looked to a future based on a Linux kernel. The successor to NetWare, Open Enterprise Server (OES), released in March 2005, offers all the services previously hosted by NetWare 6.5, but on a SUSE Linux Enterprise Server; the NetWare kernel remained an option until OES 11 in late 2011. NetWare 6.5SP8 General Support ended in 2010; Extended Support was available until the end of 2015, and Self Support until the end of 2017.

NetWare evolved from a very simple concept: file sharing instead of disk sharing. By controlling access at the level of individual files, instead of entire disks, files could be locked and better access control implemented. In 1983 when the first versions of NetWare originated, all other competing products were based on the concept of providing shared direct disk access. Novell's alternative approach was validated by IBM in 1984, which helped promote the NetWare product.

Novell NetWare shares disk space in the form of NetWare volumes, comparable to logical volumes. Client workstations running DOS run a special terminate and stay resident (TSR) program that allows them to map a local drive letter to a NetWare volume. Clients log into a server in order to be allowed to map volumes, and access can be restricted according to the login name. Similarly, they can connect to shared printers on the dedicated print server, and print as if the printer is connected locally.

At the end of the 1990s, with Internet connectivity booming, the Internet's TCP/IP protocol became dominant on LANs. Novell had introduced limited TCP/IP support in NetWare 3.x (c. 1992) and 4.x (c. 1995), consisting mainly of FTP services and UNIX-style LPR/LPD printing (available in NetWare 3.x), and a Novell-developed webserver (in NetWare 4.x). Native TCP/IP support for the client file and print services normally associated with NetWare was introduced in NetWare 5.0 (released in 1998). There was also a short-lived product, NWIP, that encapsulated IPX in TCP/IP, intended to ease transition of an existing NetWare environment from IPX to IP.

During the early to mid-1980s Microsoft introduced their own LAN system in LAN Manager, based on the competing NBF protocol. Early attempts to compete with NetWare failed, but this changed with Windows NT and the windows Domain concept, which, offered similar functionality to NetWare's eDirectory services, but on a system that could also be used on a desktop, and due to the vertical integration there was no need for a third-party client.