Software was a collection of programs and instructions that ran on computer hardware.
Data, an android, utilized software written by Noonien Soong to dictate his responses. In 2365, Commander Bruce Maddox wished to run a full diagnostic on Data and evaluate the condition of his current software, then dump his core memory into the Starbase 173 mainframe computer. Data had reservations with Maddox's plan due to the fact that it lacked specifics necessary to support the experiment. (TNG: "The Measure Of A Man")
The Iconian probe encountered by the USS Enterprise-D in 2365 transmitted a computer program to the starship which started rewriting the ship computer's software in its own image. (TNG: "Contagion")
In 2373, the Long-term Medical Holographic program was loaded with the basic software of the Emergency Medical Holographic program, with plans to update it with aspects of Julian Bashir's personality. Upon the test program encountering Deep Space 9's EMH, the former recommended deleting the latter, referring to it as an "archaic piece of software". (DS9: "Doctor Bashir, I Presume")
Earth Starfleet software developers[]
Earth Starfleet utilized software developers in the 22nd century to create the flight software used by starships. The following Starfleet members developed the flight software used by Enterprise NX-01: (Star Trek: Enterprise set artwork)