9.Debt, 10. Book Debt, 11. Good Debt, 12. Bad Debt and 13. Doubtful Debt:

9. Debt:
     The amount due from a debtor to the business is called a debt.

10. Book Debt:
     Book Debt is nothing but debt. It is called book debt, as it is the amount due from the debtor ad per the books of account.

11. Good Debt:
     Good debt refers to fully recoverable debt.

12. Bad Debt:
     A debt which is irrecoverable is called a bad debt.

13. Doubtful Debt:
     A debt whose recovery is doubtful is called a doubtful Debt.