What are the meaning of insidertrading and junk bond ??

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Thanks phales6eny for your answer ,, it is so clear ,, I tried to Understand those terms from the net ,, but also I didn't understand them so thx alot but I have question also ,, what is the effect of junk bond on the company .. ?? I have a case about a murder and something related to issue junk bonds and insider trading ,, and I have to analyse this case carefully to solve the puzzle and do presentation in the university‏