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Oldie but goodie: https://youtu.be/EnSu9hHGq5o Loop like a native: while, for, iterators, generators presented by Ned Batchelder More on reddit.com

If we stay with the example of a list, think of it this way: Imagine you have a list with elements [a,b,c] And you need to loop through the list for some action The question then is, do you need the actual elements, for example because you want to validate them or something? In that case going with the actual element in "for i in list" is the way to go. However, if you need the indexes of the items, for example for comparing or checking where in an ordered list items are, going with "for i in range(len(list))" is the way to go, as it allows you to check the current element of the list with a simple "list[i]" while being able to do something with the index itself. Ideally very often you would use something more descriptive than "i" if you need to do a bigger operation with it in order to makeit clear to the reader of your code what the selected item/index is for Please excuse my poor code formatting, I am on mobile, but I hope this helped you a little.. TLDR: It depends on use case which way to use for loops More on reddit.com

The index(), count() and other "functions" you mention aren't standalone functions, they are methods of lists. That means you apply them to the list, like this: test = [1, 2, 3, 4, 5, 6] print(test.index(3)) # print index in list of the element of value 3 The list methods are described in the documentation . More on reddit.com