What are "_vti_cnf", "_vti_pvt", "_vti_script" and "_vti_txt" folders?

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

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.