what does "pun intended" mean in this context [closed]

Firstly a pun is a joke based on the different meanings of the same word or two or more similar sounding words.

The specific example is what is called an in-joke which is a joke which is appreciated only by a small group of people and is funny only because they have shared experiences. If you are not already familiar (as I was not) with the concept of transmedia storytelling it means nothing.

However I have found that Henry Jenkins was one of the co-authors of a book called Spreadable Media which, it seems, has gone on to be the foundation of the transmedia movement.

Henry Jenkins is then reported to be "spreading" the news about transmedia. The pun is a play on the fact that Professor Jenkins wrote a seminal book called "Spreadable Media" and is now "spreading the news".

Many puns of that nature are accidental or unavoidable and are often followed by the phrase "no pun intended" in parentheses but the author of the piece is saying that his use of the pun is intentional.