What is an "alternative data stream" used for?

An alternative data stream is a feature of the NTFS file system that allows additional data to be associated with a file without altering the visible content or the file size that is normally displayed. This capability is particularly significant in contexts like cybersecurity, where it can be used for purposes such as adding metadata or attaching hidden information to files. These streams can hold information like comments, author names, or even hidden instructions that could be utilized by software without affecting the main file's characteristics.

This functionality is foundational in understanding how data can be stored and manipulated within files, especially concerning security threats, as malicious actors might exploit alternative data streams to conceal malware or other harmful data from users and traditional scanning tools. Understanding the role of alternative data streams is crucial for cybersecurity professionals who need to identify and manage potential risks associated with hidden data.