What do ellipsis […] mean in a list?

I was playing around in python. I used the following code in IDLE: The output was: What is this […]? Interestingly I could now use this as a list of list of list up to infinity i.e. I could write the above as long as I wanted and it would still work. EDIT: How is it represented in memory? What’s its use? Examples of some cases where it is useful would be helpful. Any link to official documentation would be really useful. Answer It means that you created an infinite list nested inside itself, which can not be printed. p