What does starting a line or item with # mean to org-mode

for example

* list item one
* list item two
  # some stuff I wrote that

Notice that the line starting with # is indented under the second list item
I can notice that the line starting with # have a different color
but does it have a different meaning now to org-mode

I personally use this to add comments in my file and comment related to the
parent item list
its like am telling myself, this is a note a comment, it is not part of the
list

But what does starting lines with # mean for org-mode

Thanks
Ali