# What does increase or decrease in marginal utility mean in terms of quantity demanded?

According to the definition of marginal utility " it is the utility or satisfaction derived from the consumption of an additional unit of any commodity."

So, the question is what does increase or decrease in Marginal Utility of a good, let's say X, will mean and how we can relate it to quantity demanded?

This whole thing came while I was going through Edgeworth-Pareto definition of Complementary and Substitute goods. Thanks in advance.