An acceleration clause, in the law of contracts, is a term that fully matures the performance due from a party upon a breach of the contract. Such clauses are most prevalent in mortgages and similar contracts to purchase real estate in installments. Law (a loanword from Old Norse lag), in politics and jurisprudence, is a set of rules or norms of conduct which mandate, proscribe or permit specified relationships among people and organizations, provide methods for ensuring the impartial treatment of such people, and provide punishments for those who do not follow... A contract is any promise or set of promises made by one party to another for the breach of which the law provides a remedy. ... Introduction A mortgage is a device used to create a lien on real estate by contract. ... Real estate is a legal term that encompasses land along with anything permanently affixed to the land, such as buildings. ...

Suppose, for example, the contract was for A to purchase Blackacre from B for $100,000, to be paid in 5 monthly installments of $20,000. If A makes the first two payments, but fails to make the third payment, an acceleration clause would require that A must immediately pay B the entire balance of $60,000, or lose his right to purchase Blackacre (without getting a refund of his $40,000). Blackacre, Whiteacre, Greenacre, and variations thereof are the placeholder names of fictitious estates in land universally used by professors of law in common law jurisdictions, particularly in the area of real property, to discuss the rights of various parties to a piece of land. ...

A sample acceleration clause reads like this:

In the event of default in the payment of any of the said installments or said interest when due as herein provided, time being of the essence hereof, the holder of this note may, without notice or demand, declare the entire principal sum then unpaid immediately due and payable.

• Promissory Note - Installment - With Acceleration Clause