In mathematics, a function is a relation between a set of inputs and a set of permissible outputs with the property that each input is related to exactly one output. A function is defined by its set of inputs, called the domain; a set containing the set of outputs, and possibly additional elements, as members, called its codomain ; and the set of all input-output pairs, called its graph. Sometimes the codomain is called the function's range, but more commonly the word "range" is used to mean, instead, specifically the set of outputs (also called the image of the function). For example, we could define a function using the rule $f(x) = x^2$ by saying that the domain and codomain are the real numbers, and that the graph consists of all pairs of real numbers $(x, x^2)$.
In 2010 the tags emerged and it is suggested to be deleted. Seems nothing had been done. There were around 500 questions tagged with "functions" in 2011. Now in 2018, we have over 19,000 questions tagged with "functions".
Probably we all know why: whenever a question involves functions, people add the "functions" tag.
Not only that this is not what the tag info suggested, but also it makes the tag useless.
My questions is: How can we discourage people from using the "function" tag?
This is what I have in mind:
Add to the tag info that one should not use the tag simply because you used functions in the questions (But really, who will read the tag info before using the tag?)
Change the name from function to mapping. (Not sure how it can be done).