Index is a normalization of your prices with average rule. To find the index of a product, we divide the price of that product to the average price for that product in the market and then multiply that with 100. This is an index of just one product. So basically, average price in the market is 100 index point and we position you according to your own index value. We calculate the index value at 2 different levels as well. Brand/Category level and all product level. While finding your all product level index, we get the average of all the indices in your account.
Here is a quick video about index!