Mark-of-the-Web (MotW) is a Windows trust marker that identifies a file as having come from the internet or another untrusted source. Windows usually stores it as metadata, often in the Zone.Identifier stream, and uses it to apply extra safety checks when the file is opened.
MotW matters because it can trigger warnings in features such as SmartScreen, helping users pause before running downloaded scripts, documents, or executables. In real attacks, malware authors try to preserve, hide, or remove MotW so a file looks less risky. If the marker is lost during extraction or copying, Windows may show fewer warnings even though the file is still untrusted. For defenders, MotW is useful provenance data, but it is not a guarantee of safety. It should be backed by patching, email and archive filtering, application control, and least-privilege execution.