VER

Display the current operating system version.

Syntax
      VER

A very simple method of version checking is to pipe a version string into FIND, however there is a possibility that something which is a unique string today might match a minor version released in the future.

e.g. the following would also match "7.6.1"

ver | find "6.1" > nul
if %ERRORLEVEL% == 0 goto ver_2008R2

Batch file to find the current operating system version:

@Echo off
For /f "tokens=4,5,6 delims=[]. " %%G in ('ver') Do (set _major=%%G& set _minor=%%H& set _build=%%I) 

Echo Major Version: [%_major%]
Echo Minor Version: [%_minor%]
Echo Build: [%_build%]
Echo Architecture: [%PROCESSOR_ARCHITECTURE%]
pause

Version / Release ID

The VER command returns the Major/Minor / Build number, but does not include the Version/Release ID as displayed in Settings > About.

The Release ID is typically a 4 digit code - a 2 digit year plus 2 digit month = the planned release date,
so 1709 means 2017 month 09 (September).
In practice the final release date can be a month or so later.

Mobile, Desktop and Server releases will have the same Version/Release ID but different build numbers.
This Release ID can be retrieved from the registry with PowerShell:
(Get-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion" -Name ReleaseId).ReleaseId

List of Windows Version numbers

Windows Version Numbers
Product name Major version / build Version / Release ID

Windows 95 4.0.950

Windows XP 5.1.2600

Windows Vista, Service Pack 2 6.0.6002

Windows 7, RTM (Release to Manufacturing) 6.1.7600.16385

Windows 7 6.1.7600

Windows 7, Service Pack 1 6.1.7601

Windows 8, RTM 6.2.9200.16384

Windows 10 Gold 10.0.10240 1507

Windows 10 November Update, 2015-11-03 10.0.10586 1511

Windows 10 Aniversary Update 2016-08-02 10.0.14393.1794 1607

Windows 10 Creators Update 2017-04-11 10.0.15063.674 1703

Windows 10 Fall Creators Update 2017-10-17 10.0.16299.19 1709

Windows 10 April 2018 Update 10.0.17134 1803

Windows 10 October 2018 Update 10.0.17763.55 1809

Windows 10 version 1903 (May 2019 Update) 10.0.18362.239 1903

Server versions
Product name Major version / build Version / Release ID

Windows Server 2003 5.2.3790

Windows Server 2008 6.0.6001

Windows Server 2008 R2, RTM 6.1.7600.16385

Windows Server 2012 6.2.9200

Windows Server 2012 R2 6.3.9600

Windows Server 2016 RTM 2016-09-26 10.0.14393 1607

Windows Server 2016 Aniversary Update 2017-03-22 10.0.14393.970 1703

Windows Server 2016 Fall Creators Update 10.0.16299.15 1709

Windows Server, version 1803 (Semi-Annual Channel) (Datacenter, Standard) 10.0.17134.1 1803

Windows Server, version 1903 10.0.18342 1903

See also Wikipedia list of Windows versions and Microsoft Windows 10 release history

Windows Version Numbers
Product name	Major version / build	Version / Release ID
Windows 95	4.0.950
Windows XP	5.1.2600
Windows Vista, Service Pack 2	6.0.6002
Windows 7, RTM (Release to Manufacturing)	6.1.7600.16385
Windows 7	6.1.7600
Windows 7, Service Pack 1	6.1.7601
Windows 8, RTM	6.2.9200.16384
Windows 10 Gold	10.0.10240	1507
Windows 10 November Update, 2015-11-03	10.0.10586	1511
Windows 10 Aniversary Update 2016-08-02	10.0.14393.1794	1607
Windows 10 Creators Update 2017-04-11	10.0.15063.674	1703
Windows 10 Fall Creators Update 2017-10-17	10.0.16299.19	1709
Windows 10 April 2018 Update	10.0.17134	1803
Windows 10 October 2018 Update	10.0.17763.55	1809
Windows 10 version 1903 (May 2019 Update)	10.0.18362.239	1903

Server versions
Product name	Major version / build	Version / Release ID
Windows Server 2003	5.2.3790
Windows Server 2008	6.0.6001
Windows Server 2008 R2, RTM	6.1.7600.16385
Windows Server 2012	6.2.9200
Windows Server 2012 R2	6.3.9600
Windows Server 2016 RTM 2016-09-26	10.0.14393	1607
Windows Server 2016 Aniversary Update 2017-03-22	10.0.14393.970	1703
Windows Server 2016 Fall Creators Update	10.0.16299.15	1709
Windows Server, version 1803 (Semi-Annual Channel) (Datacenter, Standard)	10.0.17134.1	1803
Windows Server, version 1903	10.0.18342	1903

Finding the version remotely

PowerShell can be used to find the OS versions of multiple machines across a domain:
Get-ADComputer -Filter {OperatingSystem -like "Windows 10*"} -Property * | Format-Table Name,OperatingSystem,OperatingSystemVersion -Wrap –Auto

Service Pack Level

This batch script or this PowerShell script will return the Service Pack level.

32 bit or 64 bit process detection

The environment variable PROCESSOR_ARCHITECTURE holds the following possible values:

64-bit process: AMD64 or IA64
32-bit process or WOW64 (32bit Program on 64 bit OS): x86

If we are running WOW64 then PROCESSOR_ARCHITEW6432 =AMD64

IF PROCESSOR_ARCHITECTURE == x86 AND
  PROCESSOR_ARCHITEW6432 NOT DEFINED THEN
  // OS is 32bit
ELSE
  // OS is 64bit
END IF

via David Wang @MSFT

Errorlevels

If the version was successfully displayed %ERRORLEVEL% = 0
If a bad parameter is given %ERRORLEVEL% = 1
VER /? will not reset the ERRORLEVEL, this is a bug.

VER is an internal command.

“Always be a first-rate version of yourself, instead of a second-rate version of somebody else” ~ Judy Garland

Related:

Win32_OperatingSystem OperatingSystemSKU - Retrieve the OS Type via WMI (sku=Stock Keeping Unit ).
Sigcheck - Check a file version, both OS files and others.
SystemInfo - Return OS, Service pack, BIOS, Memory etc.
WINVER.exe - Opens the GUI Version dialogue box (Help, About)
Wikipedia - Timeline of Microsoft Windows
PowerShell equivalent: get the Operating System version
Equivalent bash command (Linux): uname -r - Print system information.