What are "_vti_cnf", "_vti_pvt", "_vti_script" and "_vti

These folders appear in my .NET Web project. Why do they appear? Are they useful?

What are _vti_cnf folders?

The “ _vti_cnf ” holds your meta data. If you delete it, you can rebuild it by Recalculating Hyperlinks. You will find one in every folder. Delete the “ _vti_pvt ” will cause you problems, in recognizing the local website. You should only see this in the main folder.

They are used as part of the FrontPage server side extensions which do

change tracking (mostly the _vti_cnf)
code/script used by FrontPage specific controls (mostly the _vti_script)
general settings

The old FrontPage program and Dreamweaver both used it.

The VTI part is actually because FrontPage was originally created by Vermeer Technologies Incorporated (note the acronym) and then bought by Microsoft and it just stuck.