lists tuples strings may be indexed, which selects an individual elements, e.g.
s[2]  selects the 3rd element of s as
indexes start from 0 ie s[0] is the first element
indexes may be negative which means counting from end of string/list
s[-1] is the last element, s[-2] is the second from last and so on
 
slice is the name of objects used to index one or more elements in a string or list or tuple
[start : end :step]
each of start end and step are optional
but at least one must be present
if step is not present the second : may be omitted
if end is not present it is taken to be end of string
s[0:]  means the entire string/list/tuple

note end is not repeat NOT included in the selection
so s[:3] selects  the first 3 elements s[0],s[1], s[2]

the same start,end,step  is used for the range function which is used to generate
a list (in effect) of numbers, often for a for loop

range(10) generates a list of 10 numbers 0,1,2,3,4,5,6,7,8,9

range(2,13,2) generates a list of even numbers 2,4,6,8,10,12

a simple for loop might be
for i in range(1,11):
	print(i)
	
you can build a list by creating an empty list and using a for loop to append to it
even_numbers = []  # empty list
for i in range(1, 11):
	print('i is {} and i squared is {}'.format(i, i*i))
	
python has a quicker, shorter syntax called list comprehension

even_numbers = [i for i in range(2,13,2)]

you can use an if statement which comes after the for

even_numbers = [i for i in range(2,13) if (i%2) == 0]

though this would be silly as you can use the previous example

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diversion

you can assign different values using if else (python's version of a conditional expression)

is_even = True if (value%2) == 0 else False

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different elements in a list can be of any type
so a list can contain other lists, or strings, or tuples or dicts
the different elements in a list don't have to be the same type, but that soon gets confusing

going back to this example
even_numbers = []  # empty list
for i in range(1, 11):
	print('i is {} and i squared is {}'.format(i, i*i))
	
another way to get the same output is
even_numbers = [(i, i*i) for i in range(2,13,2)]
for el in even_numbers:
	print('i is {} and i squared is {}'.format(el[0], el[1]))
	
though you could argue the list name (even_numbers) is a bit misleading


finally you can have 

[(i,j) for i in range(1,10) for j in range(1,5)]