many reasons exist to store set of numbers for exampleyou'll need to keep track of the positions of each character in gameand you might want to keep track of player' high scores as well in data visualizationsyou'll almost always work with sets of numberssuch as temperaturesdistancespopulation sizesor latitude and longitude valuesamong other types of numerical sets lists are ideal for storing sets of numbersand python provides number of tools to help you work efficiently with lists of numbers once you understand how to use these tools effectivelyyour code will work well even when your lists contain millions of items using the range(function python' range(function makes it easy to generate series of numbers for exampleyou can use the range(function to print series of numbers like thisnumbers py for value in range( , )print(valuealthough this code looks like it should print the numbers from to it doesn' print the number in this examplerange(prints only the numbers through this is another result of the off-by-one behavior you'll see often in programming languages the range(function causes python to start counting at the first value you give itand it stops when it reaches the second value you provide because it stops at that second valuethe output never contains the end valuewhich would have been in this case to print the numbers from to you would use range( , )for value in range( , )print(valuethis time the output starts at and ends at working with lists