What Is Windows Kernel Transaction Manager

The Kernel Transaction Manager (KTM) enables the development of applications that use transactions. The transaction en,gine itself is within the kernel, but transactions can be developed for kernel- or user-mode transactions, and within a single host or among distributed hosts.
The KTM is used to implement Transactional NTFS (TxF) and Transactional Registry (TxR). TxF allows transacted file system operations within the NTFS file system. TxR allows transacted registry operations. KTM enables client applications to coordinate file system and registry operations with a transaction.
To develop an application that coordinates transactions with resources other than TxF or TxR, you must first develop a Win32 transaction-aware service, also called a resource manager.
Managed and COM+ applications should use their native transaction managers.

Where Applicable
KTM can be used with applications and resource managers hosted on Windows Vista or Windows Server 2008.

Developer Audience
The KTM API is designed for use by C and C++ programmers.

Run-Time Requirements
KTM is supported starting with Windows Vista.

Source: Microsoft