Windows 10 version 1607 was released in August 2016. Since then, Microsoft has released a few major updates for the Windows 10 platform, including Creators Update (version 1703) and Fall Creators Update (version 1709). At the same time, previous Windows 10 versions have received a bunch of cumulative updates, including security fixes and stability improvements.
Along with the change log for today's Patch Tuesday update for Windows 10 1607, the support page contains the following note.
Windows 10 version 1607 will reach end of service on April 10, 2018. Devices running Windows 10 Home or Pro editions will no longer receive monthly security and quality updates that contain protection from the latest security threats. To continue receiving security and quality updates, Microsoft recommends updating to the latest version of Windows 10.
As of April 10, all consumer SKUs of Windows 10 will no longer receive updates. Windows 10 Enterprise and Education editions will continue to receive updates for six months till October 9, 2018. Also, the long-term servicing channel will receive updates till October 2026.
Finally, today is the end of support for Windows 10 version 1511 Enterprise and Education.
Running the older version of Windows 10 may allow hackers to potentially execute harmful code on your devices via newly discovered yet unpatched security holes. So if you're concerned about your security, don't forget to upgrade to the latest version of Windows 10.
If you need to find out which version of Windows 10 you have installed, see the following article:
To get the latest stable release of Windows 10, refer to the following tutorial: