Suppose there is a part of program that does not deal with initialisation, input, output. It just specifies what should be done, what is allowed or not. I use the term "Business logic" for this. But application can have nothing to do with business.
Example: a game. Suppose there are following parts:
- Input processing
- Collision detection, physics, player control
- Rendering the output
- AI - How do NPCs attain the specified goal.
- "Business logic" - what happens when player touch certain objects. What types of NPCs are there and what they do when ..., concepts of "lives", "ammo", "levels", "score".
But it is not business, it's just a game. Wikipedia is not clear about it.