I have found multiple definitions of what a heuristic is, and I have found multiple computer science-related definitions.
In my university course, the lectures cite the Nielson Norman Group defining a heuristic as an area of measurement. On Wikipedia, a heuristic is defined as a problem-solving technique. These definitions do not seem to be referring to the same thing.
In the context of human-computer interaction, what is a heuristic?
you might aswell ask this qustion over at https://ux.stackexchange.com/. But you are a CS guy so you probably didn't touch that UX part yet.
Heuristics as defined by Nielson et al. can be used to evaluate the usability of a user interface. They describe common-sense approaches to identify usability issues with user interfaces. Therefore these heuristics are "problem-solving technique": A technique to identify problems in user interfaces.
As children grow up, they learn heuristics like "if it smells bad - don't eat it" or "if something is red - be careful, it might be hot".
And for UI heuristics it is similar: "If the error message does not say what the problem is - users will not be able to solve it.", "If I can see/visit/input forms that dont apply to me - Users will get lost." or "If I cant use or customize keyboard shortcuts - experienced users can not start to work more efficiently."
These ARE concrete heuristics - each is a technique to identify (and solve) usability problems in user interfaces.
