The 12 Hive in MOSS 2007 Explained

The legendary 12 hive folder is where the OOB system files are located afterSharePoint 2007 installation. 

It is located at "C:\Program Files\Common Files\Microsoft Shared\web server extensions\12" in a standard MOSS 2007 installation. This folder contains the following sub-directories:

• ADMISAPI - This folder maps to IIS virtual directory  for SharePoint Central Administration web service
• BIN - MOSS utilities binary files such as STSADM.EXE. Sub-directory LCIDD stores language specific binary files in individual folders for each language. 
• CONFIG - As the name suggests configuration files used by MOSS
• Data - Indexing services save indexes here.
• HCCab - A set of cab files containing manifest and content information used by the SharePoint help sytem are stored in LCID subdirectory
• Help - The help files used by the configuration wizard
• ISAPI - This folder maps to IIS virtual directory "_vti_bin" and stores all the standard Web Services for SharePoint except SharePoint Central Administration.
• LOGS - SharePoint logs.
• Resources - Localization resources for SharePoint sites
• TEMPLATE - The templates for a SharePoint web site. The features and xml files are also stored in subdirectories of this folder.

A snapshot of 12 hive folder (Click image to zoom)