Windows 10 is being billed as the last version of Windows ever.
Every year Microsoft is coming out with two significant updates to the Windows 10 OS. While the naming scheme is beyond retarded, the numbering scheme is simple. First two digits are the release year, second two are the completed (not release) month.
1507 - Original release of Windows 10 - July 2015
1511 - November Update - Nov 2015
1607 - Anniversary Update - Aug 2016
1703 - Creators Update - April 2017
1709 - Fall Creators Update - Oct 2017
1803 - Spring Creators Update - April 2018
1809 - ???? - Oct 2018
Everyone of these significant updates is basically an in-place OS upgrade. Like going from Windows 95 to 98 or from 2000 to XP, using an Upgrade disc.
For large Enterprise Microsoft has Windows 10 LTSC, which can only be obtained via volume licence. LTSC does not get the big updates and new releases are slated for every 2 or 3 years. I believe the current edition is 1607, and a new version isn't slated unit 2019. It makes sense for organizations that lease. If you are on a three year lease and opt for Enterprise LTSC, and time it out just right, you will hardly ever be without the latest version of Windows for that sku.
I am a big proponent of fresh installs and never have done a upgrade. At least once a year, every year since 1997 or so, I made it a point to reformat and reinstall Windows. So with 10, I continue that tradition, knowing that every April and October will be my reformat and rebuilt months. All but one of my four Windows 10 machines has an SSD, so it really doesn't take that long. I download the latest ISO from Microsoft using the Media Creation Tool, copy my Docs, Pics, Videos folders to my NAS, run a format c: over night, when I wake up I have 4 blank computers and and go down the chain one by one and run the Window installer and reinstall the software. By noon I'm mostly all set, and I have absolutely none of the problems you read about online from people who let Windows Update update and install the latest release.