The purpose of the M5 Competition is to replicate the results of the previous four ones and extend them into two directions. First increasing the number of series to 10,000, and second including machine learning (Neural Network) forecasting method. Information about forecasting methods and their comparisons can be found in the textbook “Forecasting: Methods and Applications” (Makridakis, Wheelwright and Hyndman, 1998). A recent study discussing the accuracy of Statistical and Machine Learning methods, explaining why the performance of the latter is below that of the former and proposing some possible ways forward,  can be found here.