It is the main Quality Management System (QMS) standard for medical devices, although several countries have their own set of regulations. As an example, the United States plans to harmonize the Food and Drug Administration (FDA) requirements for medical devices with ISO 13485. The scope of the QMS can be tailored for an organization, particularly in Section 7. The current version is ISO 13485:2016, which was published in March of 2016 (thus the: 2016).

It does NOT matter what size your organization is: 1 person or 1 million people
It is NOT a standard for products. It does not define product quality. This is a process-based standard: you use it to control your processes, then your end product should meet the desired results.
It is NOT a personal standard – a person cannot get certified to ISO 13485. Instead, an organization or company becomes certified. An individual, however, CAN become an ISO 13485 Certified Lead Auditor after a 5-day training course. This then allows them to audit other companies.
It is NOT a membership group. An organization cannot “join” ISO 13485. To become ISO 13485 certified, your organization must:
Follow the steps to implement an ISO 13485 quality management system.
Then a Certification Body (CB or Registrar) audits the performance of your organization against the latest version of the ISO 13485 Requirements. If you pass this audit, the Registrar issues an ISO 13485 Certificate demonstrating that your organization is Registered to ISO 13485 for a three year period. (See Who is able to grant certification)
Finally, the organization must be re-certified every three years in order to maintain its ISO 13485 certification status.