TASK DEFINITION: In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
PROBLEM: Marginal utility is a concept from economics that describes the change in utility from consuming more or less of a good or service .

SOLUTION: In economics , utility is the satisfaction or benefit derived by consuming a product ; thus the marginal utility of a goods or service is the change in the utility from an increase in the consumption of that good or service .

PROBLEM: A game controller is a device used to play video games .

SOLUTION: A game controller , or simply controller , is an input device used with video games or entertainment systems to provide input to a video game , typically to control an object or character in the game .

PROBLEM: Christmas is celebrated all over the world , as a religious holiday or as a time of celebration by Christians and non-Christians alike .

SOLUTION:
Christmas Day is a public holiday in many of the world 's nations , is celebrated religiously by a majority of Christians , as well as culturally by many non-Christians , and forms an integral part of the holiday season centered around it .