The contour interval of a contour map is the difference in elevation between successive contour lines. More generally, a contour line for a function of two variables is a curve connecting points where the function has the same particular value. The gradient of the function is always perpendicular to the contour lines.
Public finance is the study of the role of the government in the economy. It is the branch of economics which assesses the government revenue and government expenditure of the public authorities and the adjustment of one or the other to achieve desirable effects and avoid undesirable ones.
Government bond. A government bond is a bond issued by a national government, generally with a promise to pay periodic interest payments and to repay the face value on the maturity date. Government bonds are usually denominated in the country's own currency. Government bonds are sometimes referred to as 'sovereign bonds'.