Questions intended to resolve a specific programming problem that have only one correct answer.
A "specific programming problem" can be defined as a problem that exists in code and that can be
resolved with correct code (or cannot be resolved at all). These questions are normally language-specific.
Questions about best practices and other aspects of programming, including use of software tools used in the development process,
standards for maintenance and readability of code, advice to avoid potential coding pitfalls, etc.
Questions that get upvoted. In other words, anything is game. The community will adjust itself without the need for defining what is appropriate and a strict overseer group that closes what they deem doesn't belong.
So called "Homework Questions" that would be at the level of a computer science course offered to high school students or first year college students. For example, something in line with the following CS 101 homework assignment.