Security

A security is a financial instrument issued by a business entity or government, which gives the buyer the right to either interest payments or a share of the earnings of the issuer. Securities form a key part of the financing structure of an economy. Examples of securities are stocks, bonds, options, and warrants. 

The concept can also refer to the collateral on a loan, which gives a lender the right to take possession of the collateral if a borrower cannot pay back a loan.