Polymer

Polymer is a substance collected of molecules with large molecular mass collected of repeating structural units, or monomers, connected by covalent chemical bonds. The word is resulting from the Greek, πολυ, polu, "many"; and μέρος, meros, "part". Well known examples of polymers contain plastics, DNA and proteins.

While the term polymer in popular usage suggests "plastic", polymers consist of a large class of natural and synthetic materials with a variety of properties and purposes. Natural polymer materials such as shellac and amber have been in utilize for centuries. Biopolymers such as proteins (for example hair, skin and division of the bone structure) and nucleic acids take part in crucial roles in biological processes. A variety of other natural polymers survive, such as cellulose, which is the major constituent of wood and paper.

Corporate bond

A corporate bond is a bond issued by a company. The term is usually applied to longer-term debt instruments, normally with a maturity date falling at least a year after their issue date. The term "commercial paper" is sometimes worn for instruments with a shorter maturity.

Sometimes, the term "corporate bonds" is used to include all bonds apart from those issued by governments in their own currency. Strictly speaking, however, it only applies to those issued by corporations.

Bill of Exchange

A bill of exchange is a printed order by the drawer to the drawee to pay money to the payee. The most general type of bill of exchange is the cheque, which is defined as a bill of exchange drawn on a banker and payable on demand. Bills of exchange are used mainly in international trade, and are written orders by one person to his bank to pay the bearer a specific sum on a specific date sometime in the future.

Prior to the advent of paper currency, bills of exchange were a more important part of trade. They are a quite ancient form of instrument: they were used by medieval trade fairs, such as the Frankfurt Trade Fair.

Public good

In financial side, a public good is a good that is non-rival and non-excludable. This means that utilization of the good by one individual does not reduce the amount of the good available for consumption by others; and no one can be successfully excluded from using that good. For example, if one individual eats a cake, there is no cake left for anyone else, and it is probable to exclude others from consuming the cake; it is a rival and excludable good, or a private good. Conversely, breathing air does not considerably reduce the amount of air available to others, nor can people be effectively excluded from using the air. This makes it a public good, These are highly hypothetical definitions: in the real world there may be no such thing as an completely non-rival or non-excludable good; but economists think that some goods in the real world approximate closely enough for these concepts to be meaningful.