what is negative test for functional testing

I am trying to understand what is a negative test case.

For example: Let's consider we have a website where we can upload a file. It should only accept text or CSV file. and it should not have more than 100 charters in width and 100 characters in length. if it's not text or csv or if width or length is exceeding it should show a proper error message.

what would be the negative tests for this?

• is uploading a file other than a text file a negative test?
• is uploading a file with 101 in length or width a negative test?

I think both of the above are a positive test case as it's not intended to break the system, it's intended to verify the error messages.

And so if you agree with above statement what should be the negative tests according to you?