1. Program Files\Common files\Microsoft Shared\Web Server Extensions\14 \

This directory related SharePoint 2010 installation, Configuration and its files. SharePoint core installation files are placed in this folder

  1. Program Files\Common files\Microsoft Shared\Web Server Extensions\14\ADMISAPI

This directory contains the soap services for Central Administration. If this directory is altered, remote site creation and other methods exposed in the service will not function appropriately.

  1. Program Files\Common files\Microsoft Shared\Web Server Extensions\14\CONFIG

This directory contains files used to extend IIS Web sites with SharePoint. If this directory is altered, Web application provisioning will not function correctly.

  1. Program Files\Common files\Microsoft Shared\Web Server Extensions\14\LOGS

This the folder where we can have all the SharePoint related logs will see. This is important if you face any problem or error in SharePoint you have to trace the logs files in this folder to get the exact error messages

  1. C:\ProgramFiles\Microsoft Office Servers\14.0\WebServices

This directory is the root directory where SharePoint back-end Web services are hosted, for example, Excel and Search.

  1. C:\ProgramFiles\Microsoft Office Servers\14.0\Data

This directory is the root location where local data is stored, including search indexes.

  1. Program Files\Common files\Microsoft Shared\Web Server Extensions\UserCode

This directory contains files used to support your sandboxed solutions

  1. Program Files\Common files\Microsoft Shared\Web Server Extensions\WebClients

This directory contains files related to the new Client Object Model. If you work with client object model this will be useful.