Python list or array:

	list = [1, 2, 3, 4]

A list must always first be initialized to be used later on in the program and the either appended to or used in some other way:
	
	list = []
	list.append(1)
	print(list)

Try out the above code in second CMD window: py lists_d_ex1.py

Notice it prints out the square brackets as well. In order to specifically target the contents within a list, especially if there is more than one item, you must iterate numerically like so:

	list = [1, 2, 3]
	print(list[0])
	print(list[1])
	print(list[2])

Try the above out with py lists_d_ex2.py

You type the name of the list and attach a square bracket to it. Within the square bracket you iterate ALWAYS STARTING FROM ZERO. In programming it is convention to start with zero in arrays and lists which is due to how programs and memory interact, however this is beyond the bounds of this course. 

Next, we must discuss dictionaries which are a more complex list for all intents and purposes.

Here is an example dictionary:

	dict = {'one': '1', 'two': '2'}

In order to differentiate between lists and dictionaries, dictionaries replace square brackets [] with curly brackets {}. You can have lists within dictionaries.

You can have dictionaries with dictionaries as well. Or a list of dictionaries with each having a dictionary of lists. Yup, it can get complex.

To access items within a dictionary, you must do this:

	dict = {'one': '1', 'two': '2'}
	print(dict['one'])
	print(dict['two'])

Try this out with py lists_d_ex3.py

As you can see, we are iterating over the dictionary, this time with a key. What is printed out is the value connected to that key. That is what a dictionary boils down to: A list of key's and their values.

Knowledge about dictionaries truly becomes handy when JSON format comes into play, which is a popular standard for internet API. Basically, when you programatically request data from an online source, using Amazon modules for example, the responses you get are in JSON format which can be navigated as a dictionary; a data tree with parents and children. This will be covered in a more advanced course.