Why this SPLITTING UP THE BILL page?

I have a group of friends, who have the habit to meet on the Weekend, cook together and enjoy their time together. They enjoy really elaborate cooking, steaming and baking, and in their house I have eaten some of the best cakes in my life; however, good cooking means buying good ingredients, and those people in this group who have time to do so, go to various shops in order to buy the food which is necessary for the cooking event. In the end, some people will have spent a lot (the "caviar group"), some people just a little bit, and some people won't have spent any money and just bring their working labor to the party, and their happy face.

Being true believers in equality of mankind, they want to SPLIT UP THE BILL afterwards, so that everyone would have paid in the end the same amount of money. Those who bought expensive stuff, should receive decent money for compensation; those who bought just a little or nothing, should pay the others, all in a fair way. 

This is easy, you think? Well, I can tell you, that although everyone in this group is highly intelligent and knows a lot of this our world, higher mathemtics is not their daily bread, and in particular, the calculation necessary for SPLITTING UP THE BILL page seems to be overly difficult to them. So when I'm in their reach, I have to do the math for them. After all, what was the point that my mother had ensured that I was studying of  mathematics at the university?

On one day, when I got a phone call again from one of the ladies in the cooking group, asking to calculate the expenses, I said - and it was meant as a joke at that time: Wouldn't it be convenient for you to have a website, where you just put in your names, and the amount of money everyone had already spent, and on the push of a button, you are told who has yet to pay how much and to whom?

A short moment of silence followed, and then I learned that this carelessly uttered remark of mine was not understood as a joke; it was taken at face value. "This would be great", the lady said.

So I wrote this page. First it was to be intended just to be used for this circle of friends, but my wife said, that maybe other people on this huge planet also could make use of it. Well, it is always wise to listen to your wife, so here we go: Use this page, or don't, but make sure always that you are having a great party time.