The full slice syntax is list[start:stop:step]. The step determines how many positions to advance between elements. With nums = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9], nums[::2] returns every second element: [0, 2, 4, 6, 8].
You can combine step with start and stop: nums[1:8:2] returns [1, 3, 5, 7]. A negative step reverses direction: nums[::-1] returns [9, 8, 7, 6, 5, 4, 3, 2, 1, 0].
The entire list reversed. This is the idiomatic way to reverse a list in Python. The step feature lets you extract every nth element, reverse order, or create other patterns from your data.