What is a negotiable instrument?

A negotiable instrument is a written contract for the payment of money and passes from one person to another as money, in such manner as to give a holder in due course the right to hold the instrument free from defenses available to prior parties. [1] 

Negotiable instruments have an integral part and role in the business world. It has an essential function in commercial business transactions in any given country and the world at large.[2] Because these instruments are negotiable, it performs different functions such as but not limited to:

a. used as a substitute for money
b. medium of exchange for most commercial transactions
c. medium of credit transactions
[1] Sundiang & Aquino, Reviewer on Commercial Law (2014).

[2] De Leon & De Leon, Jr. The Law on Negotiable Instruments. (2016).