A standards organization is a company that develops and amends technical standards for the inter-operability of hardware or software, as well as a way to test and certify that products comply with the standard.
Compliance with standards is sometimes voluntary, but some standards become mandatory when they are adopted by regulators as legal requirements in particular domains. It is regulatory standards, for example, that result in widely usable light-bulb sockets, electrical outlets, safety certifications for electrical equipment, etc.
A formal standard has been approved by the standards-setting organization. A de jure standard is mandated by legal requirements and may also refer to any formal standard. In contrast, a de facto is a standard that has achieved widespread use and acceptance without having been approved by any standards organization.