Margin is the difference between the selling price and the cost of producing or providing a product or service. It is often expressed as a percentage and represents the profit margin or markup.
For example, a retailer may sell a product at a 20% margin, which means that the selling price is 20% higher than the cost price.
In terms of investments, you can also buy equities and other securities on margin. This refers to amount you have taken as a loan from a broker or a firm as opposed to the total worth of the asset.