The Kahan Summation algorithm is a way to add numbers together that helps you get a more accurate answer. It works by looking at the number you are adding and seeing if it is bigger or smaller than the one that came before it. If the number you are adding is bigger, then it adds it to the total normally. If the number is smaller, it will add it to the total, but it will also add a tiny bit to make up for the tiny bit that was lost when the last number was added. After adding all the numbers, you have a more accurate answer than you would if you had just added the numbers normally.