Purpose of inserting folder: A4A5 and A3 are paper senior colonel A4 is the size of ordinary copy paper, and A3 is twice that of A4. A5 is half the size of A4.

For example, some store pictures, some store programs, and some store text information. Each kind of information can be stored in computer memory in one or more file formats. Each file format usually has one or more extensions that can be used to identify it, but it may not have an extension. A file format whose extension can help an application recognize it.

Missing folder option:

Click and select the "Start → Run" command, enter "gpedit.msc" in the "Open" column of the "Run" dialog box, and then click the "OK" button to start the Windows XP Group Policy Editor. Expand User Settings → Manage Templates →Windows Components →Windows Explorer.

Double-click the "Delete Folder Options from Tools Menu" menu on the right, and then select the "Enable" option in the pop-up dialog box to hide the folder options. If you select Not Configured or Disabled, you can display folder options.

But what about Windows xp? There is no group policy editor in the home edition system, which can be solved by running "Regedit" to open the registry editor and expand it in turn.