The Zombie Stack Exchanges That Just Won't Die
Academic libraries are libraries with the primary purpose of serving members of their post-secondary educational institutions rather than, e.g. members of the general public or another sort of institution.
This is part of a non-overlapping categorization of libraries along with public-libraries, school-libraries (for primary and secondary education), government-libraries, corporate-libraries, and others. Many or most academic libraries are also research-libraries, although that tag should not be included if not immediately relevant to the question.
This tag should be used to indicate questions about academic libraries as an institution or that would almost exclusively occur in the context of academic libraries.