The FileSystemObject object is used to access the file system on a server.
More Examples

Does a specified file exist?
How to check if a file exists.

Does a specified folder exist?
How to check if a folder exists.

Does a specified drive exist?
How to check if a drive exists.

Get the name of a specified drive
How to get the name of a specified drive.

Get the name of the parent folder of a specified path
How to get the name of the parent folder of a specified path.

Get file name
How to get the file name of the last component in a specified path.

Get the file extension
How to get the file extension of the last component in a specified path.

Get the base name of a file or folder
How to get the base name of a file or folder, in a specified path.
The FileSystemObject Object

The FileSystemObject object is used to access the file system on a server.

This object can manipulate files, folders, and directory paths. It is also possible to retrieve file system information with this object.

The following code creates a text file (c:\test.txt) and then writes some text to the file:
<%
dim fs,fname
set fs=Server.CreateObject("Scripting.FileSystemObject")
set fname=fs.CreateTextFile("c:\test.txt",true)
fname.WriteLine("Hello World!")
fname.Close
set fname=nothing
set fs=nothing
%>