Definition - What does Margin mean?
A margin refers to a boundary line where two separate properties, or borders of land or water meet. It can also refer to an amount of equity in securities purchased by a customer on credit from a broker. Finally, a margin can refer to the difference between the sale price and manufacturing price.
In the context of the law, margins can be used to delineate the legal boundaries of properties. Also, investors buying securities "on margin" must follow the laws regarding the taking on of broker credit.
Justipedia explains Margin
Margins can be very useful in surveying and in property transactions. For example, a person may wish to buy a property that borders a river. In this case, the river may serve as a margin to represent the end of the property.
In the financial world, the concept of "margin" or buying securities on a broker's credit, allows investors to buy securities that they may otherwise be unable to afford. This simultaneously allows the investor to be able to invest more, and allows the broker to be able to complete more transactions.