I'm learning Python and I don't understand this notation

Question

Note how the start is always included, and the end always excluded. This makes sure that s[:i] + s[i:] is always equal to s:

>>> word[:2] + word[2:]
'Python'
>>> word[:4] + word[4:]
'Python'

I don't understand what thee above notation is.

Answer 1

The python indices are as below

P   y   t   h   o   n
0   1   2   3   4   5 

So if you ask s[0:1] it is start index of 0 to end index of 1. Thus only P
So if you ask s[4:], anything right of index at 4(start).
So if you ask s[:4], anything left of index at 4(end).

Answer 2

If the word is Python

This means each letters index will be as follows and you can select each letter by this method

P = word[0]
y = word[1]
t = word[2]
h = word[3]
o = word[4]
n = word[5]

You can also select a range or letter by using slice notation. This uses the : in between the desired range

So...

word[2:4]

This will select the letters in index [2] and [3] but will NOT include the last index number [4]

If you leave it blank word[:] you will return the whole string Python because it will include everything from the start to the end.

If you use word[:2] it will return Pyt

If you use word[2:] it wil return thon note that the last letter is included when the right side is left blank.