A definition of marketing — The presentation of a product or service that solves a problem for the potential purchaser.
Until a person solves another person’s problem, no money changes hands–there is no commerce.
This may seem entirely too simple, yet it contains all the necessary elements. It avoids the argument of whether such things as sales or public relations are part of marketing. In our opinion they are.
On the other hand, there can be many, more refined definitions, such as the 72 in this article by the marketing genius, Heidi Cohen.
So, take your pick but don’t waste much time on it.