Can somebody tell me that why most of the operating systems having the i386 folder.:;)

The i386 folder is the directory from which Windows was installed. It's the directory from which Windows can be modified, repaired, etc. It's not absolutely required if you have the installation CDs. It's possible that there will be more than one i386 folder on your hard drive as certain drivers and other programs create i386 folders and put one or a few files in them. Servvice Packs may also create one or more, and leave them on the hard drive.

What is the i386 folder?