One tradition I read claims that mascarpone got its name from mascherpa, which is how ricotta is called in parts of Lombardy. Both dairy products are creamy, but that is where their resemblance ends. While ricotta is made with whey (byproduct of cheese making), mascarpone is made with fresh cow milk cream (panna).
Smelling delicately of cream, mascarpone can be eaten by itself or used as an ingredient for desserts, like Tiramisu. When I was a child, I would eat it sprinkled with sugar and decorated with a candied cherry.
The mascarpone made in this country is neither as flavorful nor as creamy as the one made in Italy. I am aware that this statement sounds like the usual grievance from an expatriate gripped by food nostalgia, but it is my experience. You may be able to find mascarpone made in Italy in a store near you and taste the difference: keep in mind though that anything imported cannot be really fresh. In any case, I recommend you add mascarpone to the list of foods to taste the next time you visit Italy: when you come back, we will compare notes.
Update: you can make mascarpone at home. In this post I describe how.