As of September 2015, the current version is ISO 9001:2015. The year identifies the year of release. The 2015 version replaced the 2008 one (ISO 9001:2008)
Note: in Australia, the Standard bears the 2016 date, because it wasn't published here until March 2016, 5 months after ISO. It's still the same standard.
Is certification to the 2008 version still OK?
Yes. Certificates issued to the 2008 one remain valid until September 2018 when the 3-year cross over period expires. If you have certification to the earlier 2008 version, you'll need to work with your certifier to arrange transition to the 2015 version.
Where does a Standard come from?
Producing a Standard is a lengthy process of gaining consensus between national delegations representing all the stakeholders concerned - suppliers, users, government regulators and other interest groups, such as customers and consumers to agree on the specifications and criteria to be applied. You can read the full process from the official ISO website - see Links, under Resources.
Author: Jane Bennett