Final answer:
The NTFS USN Journal is a change tracking log file located in the \$Extend\$UsnJrnl file on the NTFS volume, logging changes like file creation, deletion, and modification for system and application use.
Step-by-step explanation:
The change tracking log file for NTFS, known as the NTFS USN Journal, is a feature of NTFS that provides a persistent log of changes made to files on the volume. It is located on the NTFS volume itself and is hidden from casual viewing. The USN Journal is part of NTFS's internal system and resides in the \$Extend\$UsnJrnl file. It is utilized by the operating system and certain applications to track changes to files, which can be handy for backup, file synchronization, and security monitoring purposes. The NTFS file system uses this log to keep track of changes such as file creation, deletion, and modification. The USN Journal is managed by the operating system and its size can be configured by an administrator but it requires specific knowledge and tools to interact with directly.