We have therefore a policy† that requires you, the asker, to unambiguously specify which game system the question is about. This means that you should specify what game system you are asking about by name – and edition, if there is more than one edition of that game system. You can do so either in the body of the question or by using the appropriate tag (see below). If you include the system name and/or edition in the title, it will likely be edited out of the title, and indicated in the body and/or tags instead.
Note that while we do allow the use of commonly accepted abbreviations for game systems (such as "D&D", "PF", or "L5R"), including using "5e" as a common shorthand for the 5th edition of D&D if sufficiently clear‡†, please endeavor to make the system as clear as possible, erring on the side of including the full name and edition in the body of the question.
†: You can read a write up of it here: What is the “Don’t Guess the System” policy? and our most recent discussion of it here: Re-revisiting the "don't guess the system" policy
‡: See this Q&A: Revisit: Is "5e" a clear enough statement of game system by a question asker to determine that the question is about D&D 5e?