The terms 32-bit and 64-bit refer to the way a computer's processor (also called a CPU), handles information. The 64-bit version of Windows handles large amounts of random access memory (RAM) more effectively than the 32-bit version. Follow the steps in the sections below to find out if your PC is running the 32-bit or 64-bit version of Windows and what edition of Windows is on your PC.
Windows 10
Press the Windows 
key
Type 'About' and select the option 'About your PC'
Under Device Specifications review the System type which details whether the system is 32 or 64-bit
Windows Vista or Windows 7
Click the Start button Picture of the Start button, right-click Computer, and then click Properties.
If "64-bit Operating System" is listed next to System type, you’re running the 64-bit version of Windows Vista or Windows 7.
If "32-bit Operating System" is listed next to System type, you’re running the 32-bit version of Windows Vista or Windows 7.
The edition of Windows Vista or Windows 7 you're running is displayed under Windows edition near the top of the window
Windows XP
Click Start, right-click My Computer, and then click Properties.
If "x64 Edition" is listed under System, you’re running the 64-bit version of Windows XP.
If you don’t see "x64 Edition" listed under System, you’re running the 32-bit version of Windows XP.
The edition of Windows XP you're running is displayed under System near the top of the window.