Use this tag for questions related to teaching application development on mobile platforms. Mobile applications are commonly referred to as "apps".
App is a term that normally refers to (smaller) applications developed for mobile platforms (phones, tablets, etc). Apps normally have constraints and requirements somewhat different from those of larger applications: memory constraints, network requirements, vendor rules, etc.
App development often requires specialized languages, libraries, and tools. They may be different for each platform.
Use this tag for questions related to teaching such app development. It is not, however, appropriate for technical app development questions. Questions about tool and language selection for teaching such development are acceptable, of course.