ADS

In the context of Windows NTFS (New Technology File System), an Alternate Data Stream (ADS) is a feature that allows data to be forked into existing files without altering the original file content or size visible to the users. This feature is derived from the Macintosh Hierarchical File System's ability to store resource forks, which could hold metadata or icons separate from file data. ADS can be used to store additional information associated with a file or directory.

When files are downloaded from the internet using a browser, Alternate Data Streams (ADS) are generated for the downloaded file, containing the URL of the download source.