Negotiable Instrument

The term 'Negotiable' means transferable by delivery and the term 'Instrument' means a written document by which a right is created in favor of some person.
According to Section 13 of the NI Act-1881, Negotiable Instrument means ' a promissory note, bill of exchange or cheque' payable either to order or to bearer. These are transferable from one person to another by mere delivery or by endorsement and delivery.

Cheque

Cheque: As per Negotiable Instrument Act-1881, Article-6
A 'Cheque' is a bill of exchange drawn on a specified banker and not expressed to be payable otherwise than on demand.
A Cheque is an unconditional order in writing drawn on  a banker signed by the drawer, requiring the banker to pay on demand a sum/certain money to or to the order of a specified person or to bearer.-Dr. Hart.

Negotiable Instrument and Non-negotiable Instrument

Negotiable Instrument:

Cheque,
Bill of Exchange,
Promissory Note,
Demand Draft(DD),
Bank Note,
Treasury Bill,
Govt. Bond,
Prize Bond

Non-Negotiable Instrument:

Postal Order,
Money Order,
Pay Order,
Share Certificate,
I.O.U ( I owe to you)

Promissory Note

Promissory Note:
As per section 4 of the Negotiable Instrument Act. 1881, 'A promissory note is an instrument in writing( not being a bank-note of currency-note) containing an unconditional undertaking signed by the maker, to pay on demand or at a fixed or determinable future time a certain sum of money only to , or to the order of, a certain person, or to the bearer of the instrument.'