An Insider Preview build is a pre-release version of Windows distributed through the Windows Insider Program for testing, feedback, and compatibility checks. These builds are signed by Microsoft and delivered on specific channels such as Canary, Beta, or similar preview tracks, which means they are meant to be installed only on devices enrolled in the program.
In cybersecurity, Insider Preview builds matter because they are part of the software trust chain. Their code signature tells Windows that the build came from Microsoft and has not been altered. Security teams use them to evaluate new defenses, patches, and platform changes before general release, while attackers may study preview builds to spot security features or bugs before they reach stable versions. If a device falls behind on the required preview build, it can lose access to the normal update path until it catches up.