Does "IndexError: list index out of range" when trying to access the N'th item mean that my list has less than N items?

If you have a list with 53 items, the last one is thelist[52] because indexing starts at 0.

From Real Python: Understanding the Python Traceback - IndexError:

IndexError

The IndexError is raised when you attempt to retrieve an index from a sequence, like a list or a tuple, and the index isn’t found in the sequence. The Python documentation defines when this exception is raised:

Raised when a sequence subscript is out of range. (Source)

Here’s an example that raises the IndexError:

test = list(range(53))
test[53]

---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-6-7879607f7f36> in <module>
      1 test = list(range(53))
----> 2 test[53]

IndexError: list index out of range

The error message line for an IndexError doesn’t give you great information. You can see that you have a sequence reference that is out of range and what the type of the sequence is, a list in this case. That information, combined with the rest of the traceback, is usually enough to help you quickly identify how to fix the issue.

Yes,

You are trying to access an element of the list that does not exist.

MyList = ["item1", "item2"]
print MyList[0] # Will work
print MyList[1] # Will Work
print MyList[2] # Will crash.

Have you got an off-by-one error?

Yes. The sequence doesn't have the 54th item.

That's right. 'list index out of range' most likely means you are referring to n-th element of the list, while the length of the list is smaller than n.

If you read a list from text file, you may get the last empty line as a list element. You can get rid of it like this:

list.pop()
for i in list:
   i[12]=....