From measurement standards (inch vs. centimeter) to bicycle helmets to apparel sizing to IEEE (Institute of Electrical and Electronics Engineers) wireless technology standards private industry, government and international organization develop uniform guidelines for a variety of reasons.
A standard is a document that contains technical specifications or other precise criteria to be used consistently as a rule, guideline, or definition of characteristics, to ensure that materials, products, processes, personnel or services are competent and/or fit for their intended purpose(s).
The National Institute of Standards and Technology (NIST)
For detailed & historical information on standards in the United States:
Organizations who develop standards: