Entertainment is a broad category type for classifying information, and an industry unto itself which spans a wide spectrum of types of businesses, products and services.
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What exactly defines the industry of entertainment may be subject to debate, especially as it relates to content pertaining to other industries, where specific content types and classifications may not be so black and white. In a certain regard, the way in which content is consumed can help to define whether or not it should be categorized as Entertainment. Entertainment, in this regard, is truly one of the most broad-spanning industries as it could potentially cover material on or from any of the other major global industries.
An example of this is:
* A Car Magazine subscribed to (and payed a monthly fee to) by a car enthusiast.
Clearly, the category of interest one can imagine the magazine being classified into for this example is "Automotive" (or "Automobiles" or something similar), however if we added information that "the car enthusiast eagerly awaits the magazine every month, has subscriptions to 3 other car magazines, and is an avid collector of classic cars and information about them, then it is easy to see that the proper category for this content, in relation to the car enthusiast, is Entertainment.