In a sense, all applications created for Linux are third-party applications in that Linux itself is only an operating system kernel. The applications that run on this kernel provide Linux with its functionality.
On the assumption that a network server will have a number of requirements, it is common practice for the Linux kernel to be bundled with various applications and provided to customers as a package, which, as discussed earlier, is called a distribution.
One aspect in which Linux certainly has the edge over other operating systems is that many Linux applications are free. Developed in the same spirit as Linux itself, and in many cases governed by the same licensing types, these free applications can seriously reduce the cost of maintaining a network server. Although it can be said that there are also free server-type applications for Windows and NetWare, there are certainly not as many of them as there are for Linux. (Note that we are referring to server applications, not applications targeted at workstation or end-user applications.)