These are those persons from whom goods are purchased on credit & amount is still payable to them.

This says that business & businessman are the two sepesepa legal entity. 

The double entry system of accounting or bookkeeping means that for every business transaction, amounts must be recorded in a minimum of two accounts. The double entry system also requires that for all transactions, the amounts entered as debits must be equal to the amounts entered as credits.

Error of Omission: If a transaction remains altogether unrecorded in the Journal, i.e. the book of original entry, it will be termed as an error of omission. It is termed as a two-sided error and such an error will not affect the agreement of the Trial Balance because the transaction is altogether omitted from being recorded in the books of accounts.
Error of Principle: When a fundamental principle of accounting is violated, while recording a transaction, it is known as an error of principle.
For example: - 1. Purchase of furniture is debited to the Purchases A/c instead of Furniture A/c.
2. Repairs of old machinery are debited to the Machinery A/c instead of Repairs A/c.

<font face="Verdana"><font style="text-shadow: rgba(255, 255, 255, 0.3) 0px 1px 1px; user-select: initial !important; line-height: 1.5em; -webkit-font-smoothing: antialiased; font-family: roboto, sans-serif; color: rgb(51, 51, 51); font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">According to the Negotiable Instruments Act 1881,”a promissory note is defined as an instrument in writing (not being a bank note or a currency note), containing an unconditional undertaking signed by the maker, to pay a certain sum of money only to or to the order of a certain person, or to the bearer of the instrument”.</font></font>

This definition mean that when a person gives a promise in writing to pay a certain sum of money unconditionally to a certain person or according to his order the document is called is a promissory note.

<font face="Verdana"><font style="text-shadow: rgba(255, 255, 255, 0.3) 0px 1px 1px; user-select: initial !important; line-height: 1.5em; -webkit-font-smoothing: antialiased; font-family: roboto, sans-serif; color: rgb(51, 51, 51); font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">Following are the features of a promissory note:</font></font>

• <font face="Verdana"><font style="text-shadow: rgba(255, 255, 255, 0.3) 0px 1px 1px; user-select: initial !important; line-height: 1.5em; -webkit-font-smoothing: antialiased; font-family: roboto, sans-serif !important;">It must be in writing</font></font>
• <font face="Verdana"><font style="text-shadow: rgba(255, 255, 255, 0.3) 0px 1px 1px; user-select: initial !important; line-height: 1.5em; -webkit-font-smoothing: antialiased; font-family: roboto, sans-serif !important;">It must contain an unconditional promise to pay.</font></font>
• <font face="Verdana"><font style="text-shadow: rgba(255, 255, 255, 0.3) 0px 1px 1px; user-select: initial !important; line-height: 1.5em; -webkit-font-smoothing: antialiased; font-family: roboto, sans-serif !important;">The sum payable must be certain.</font></font>
• <font face="Verdana"><font style="text-shadow: rgba(255, 255, 255, 0.3) 0px 1px 1px; user-select: initial !important; line-height: 1.5em; -webkit-font-smoothing: antialiased; font-family: roboto, sans-serif !important;">It must be signed by the maker.</font></font>
• <font face="Verdana"><font style="text-shadow: rgba(255, 255, 255, 0.3) 0px 1px 1px; user-select: initial !important; line-height: 1.5em; -webkit-font-smoothing: antialiased; font-family: roboto, sans-serif !important;">The maker must sign it.</font></font>
• <font face="Verdana"><font style="text-shadow: rgba(255, 255, 255, 0.3) 0px 1px 1px; user-select: initial !important; line-height: 1.5em; -webkit-font-smoothing: antialiased; font-family: roboto, sans-serif !important;">It must be payable to a certain person.</font></font>
• <font face="Verdana"><font style="text-shadow: rgba(255, 255, 255, 0.3) 0px 1px 1px; user-select: initial !important; line-height: 1.5em; -webkit-font-smoothing: antialiased; font-family: roboto, sans-serif !important;">It should be properly stamped.</font></font>

<font face="Verdana"><font style="text-shadow: rgba(255, 255, 255, 0.3) 0px 1px 1px; user-select: initial !important; line-height: 1.5em; -webkit-font-smoothing: antialiased; font-family: roboto, sans-serif; color: rgb(51, 51, 51); font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">A promissory note does not require any acceptance because the maker of the promissory note himself promises to make the payment.</font></font>