[frameworks] What is middleware exactly?

There are (at least) three different definitions I'm aware of

  • in business computing, middleware is messaging and integration software between applications and services

  • in gaming, middleware is pretty well anything that is provided by a third-party

  • in (some) embedded software systems, middleware provides services that applications use, which are composed out of the functions provided by the hardware abstraction layer - it sits between the application layer and the hardware abstraction layer.