A list is a sequence of objects, separated by commas, the whole enclosed within brackets. The objects can be identified within the list by location within the sequence, specified by an integer called an index. The first index is always zero.
► The objects can be, and often are, referred to as elements of the list; as you note, they are likewise referred to as items in the list.
almost any group of symbols can be a variable (there are a few restrictions - a variable can’t begin with a number, for instance), and when the Python interpreter sees a sequence of symbols not surrounded by quotes, and not a known keyword such as def, it will assume that is a variable. If the variable has never been assigned a value, then an error will be raised:
Traceback (most recent call last):
File "C:\path\to\test.py", line 1, in <module>
NameError: name 'a' is not defined
a = 7
If the symbol is surrounded by single or double quotes, it will be interpreted as a string.