Comments should
give the reader the background of the programmer.
be written for every line of code.
communicate the purpose of the code that follows it.
give information about how many hours it took to write the code.

communicate the purpose of the code that follows it.

Explanation:

Comments should  :

- give the reader the background of the programmer.

No.  No importance the background of the programmer, it doesn't matter if he's a self-learner or went to Harvard.

- be written for every line of code.

No.  That would make the code illisible.  Might comment a specific line now and then because it is very complicated, but not every single line.  If the reader can't understand an IF structure, he shouldn't reading code.

- communicate the purpose of the code that follows it.

YES. A comment should describe the purpose of the following block of code.  It's important to know what are the inputs of a block of code and its outputs... where does the input comes from and what the output will be used for.  Sometimes it's obvious, other times no.

- give information about how many hours it took to write the code.

No.  It shouldn't have any importance.  We all know that we spend 80% of the time working on 20% of the code.  We all have been stumbled by a missing semi-coma.

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