There is no single accepted definition for standards, but Charles Sullivan describes them as:
"... a category of documents whose function is to control some aspect of human endeavor."
which is a good working definition. Standards, for our discussion, include standards, specifications, regulations, and guidelines. They help clarify, guide and control processes and activities crucial to our everyday functioning and lives. In particular, they specify definitions, performance, and design criteria (so that, for example, automobile brakes work as expected). They help create a common language with which engineers, researchers, businesses, and students can communicate, create, and learn.
Standards can be voluntary or mandatory, and as technology and needs change, become superseded. They are created by industrial societies and government bodies, in the United States and in foreign countries. They are numerous, and growing. Originally discussed by the LaQue report in 1961, the United States standards environment has been short on coordination and long on independent action among the standards issuing bodies. The situation is a little better today, but currently there are more than 550 standards-issuing bodies in the United States, as compared to 350 in 1961.
The world has taken steps to improve the standards situation. After World War II, the American National Standards Institute (ANSI) helped two fledgling international organizations, the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC), increase their roles in the standards arena. Today international standards are an important and growing area as well, with over 7000 ISO standards currently.
These are standards whose use is theoretically voluntary, but in practice is widely adopted for the sake of ease of manufacture, interchangeability, and safety. Virtually all industrial standards are voluntary standards. At times, such standards have been used in an exclusionary way, to favor one group or organization over its rivals.
Mandatory standards are, in effect, laws. Failure to follow them could result in legal penalties and liability. They are generally adopted out of concern for safety, and promulgated by the Federal government or one of its agencies or departments. Codes are groups of standards on the same topic, generally created for government agencies, and are thus mandatory standards.
These standards specify the performance levels of a particular item or process, such as a grade of steel or test methods. It doesn't matter how a thing is made or done, but it must meet a certain level performance. That performance can be on a spectrum, with major points designated as a grade or class.
Criteria standards discuss how to go about an activity, kind of the "opposite" of a performance standard. Criteria standards set up recommendations considering certain aspects of an activity, such as bridge building, or a laboratory process.
Because quality, technology, and human needs change, standards change. Sometimes the area covered by the rules of a new standard must change to meet the new guidelines. Other times, only new activities must conform. Superseded standards provide information on how things used to be done, and provide valuable information when an older area of activity (like the capabilities of an old elevator or results from a lab using older reporting techniques) is being evaluated. The Art, Architecture & Engineering Library has a large number of superseded standards in our collection.