Silver Certificates are a type of representative money

Representative money

The term representative money has been used variously to mean:*a claim on a commodity, for example gold certificates or silver certificates. In this sense it may be called 'commodity-backed money'....

 printed from 1878 to 1964 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 as part of its circulation of paper currency. They were produced in response to silver agitation

Free Silver

Free Silver was an important United States political policy issue in the late 19th century and early 20th century. Its advocates were in favor of an inflationary monetary policy using the "free coinage of silver" as opposed to the less inflationary Gold Standard; its supporters were called...

 by citizens who were angered by the Fourth Coinage Act

Fourth Coinage Act

The Fourth Coinage Act was enacted by the United States Congress in 1873 and embraced the gold standard and demonetized silver. Western mining interests and others who wanted silver in circulation years later labeled this measure the "Crime of '73"...

, which had effectively placed the United States on a gold standard

Gold standard

The gold standard is a monetary system in which the standard economic unit of account is a fixed mass of gold. There are distinct kinds of gold standard...

. The certificates were initially redeemable in the same face value of silver

Silver

Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...

 dollar coins

United States dollar coin

Dollar coins have been minted in the United States in gold, silver, and base metal versions. The term silver dollar is often used for any large white metal coin issued by the United States with a face value of one dollar, although purists insist that a dollar is not silver unless it contains some...

, and later in raw silver bullion. Since 1968 they have been redeemable only in Federal Reserve Notes and are thus obsolete, but are still valid legal tender

Legal tender

Legal tender is a medium of payment allowed by law or recognized by a legal system to be valid for meeting a financial obligation. Paper currency is a common form of legal tender in many countries....

.
There are a few features that distinguish a Silver Certificate.
The seal

Seal of the United States Department of the Treasury

The United States Treasury Seal is the official symbol of the United States Department of the Treasury. It actually predates the department, having originated with the Board of Treasury during the period of the Articles of Confederation. It is used on all U.S...

 and serial numbers on many of the first Silver Certificates issued were red, brown, and blue.