How to Install Windows 7/8.1 from a USB flash drive

Install Windows 7/8/8.1 from a bootable pendrive or flash drive is very easy than bootable CD/DVD.You can easily reduce the installation time at least 15 minutes if you compared with any CD or DVD 

 I think it is the best way to the installation of windows 7/8/8.1 via a bootable flash drive .

But another important condition is, you must be ensure that your PC's hardware that means motherboard supports USB booting.Now-a-days almost PC/Laptop supports this feature.
Your installation time will easily go faster if you use USB 3.0 flash drive instead of USB 2.0.Your flash drive need to be at least 4GB memory.It doesn't need to be
16GB or 32GB.
Now I am going to express a guideline so that you can easily install your expected OS perfectly in your laptop or PC.

Requirements:

1. Windows 7/8/8.1 DVD install disc
2. USB Drive (4GB or higher) 
3. Any Windows Operating system 

Process:

1. At first Plug in your USB drive in the USB port
2. Before plug in you can move all  important files on your drive to a safe location if you want. Insert your disc of Windows 7/8/8.1 into the computer, but don’t start the normal install process.
3. Open  My Computer and remember the drive numbers of both the USB drive and the DVD drive.
4. then open the command prompt with admin rights. Type cmd in Start menu search box and press enter
   you will see this administrator command box.it means what you type into the command prompt 
   

     5.Next type DISKPART
       then loads the diskpart application
       

        Then type

       LIST DISK

        the image above shows our 32 GB USB drive is listed as DISK 2

        so you have to type

      

       SELECT DISK 2

        You will get a successful message “Disk 2 is now the selected disk”

        

        Next we want to clean the USB drive

        Type:

       CLEAN
        you will get a successful message ‘DiskPart succeeded in cleaning the 
       disk'

      Then Type step by step which is give below:

    CREATE PARTITION PRIMARY
    SELECT PARTITION 1
    ACTIVE
    FORMAT FS=NTFS
    this will format the usb drive and will take 10-15 minutes depending on the USB drive size.
     you will get a successful message ‘100 percent completed
                               DiskPart successfully formattted the volume' 


    
    Next type:
   ASSIGN
   EXIT (the message show leaving diskpart)

  Go back to the command prompt  and type in D: CD BOOT (substitute your DVD drive  letter for "D:", if necessary) and press Enter
    then  type
   CD BOOT and press Enter
    then type
   BOOTSECT.EXE /NT60 H:(substitute your USB flash drive letter for "H:", if necessary)\
   press Enter

Now  the system to create a boot sector file on the USB drive.
Now you can exit the command prompt  The next step is to copy the entire contents of the Windows DVD to your USB flash drive
Your USB flash drive is now set up to be a bootable USB drive for Windows
You can now restart your pc and boot from the USB hard drive