A Developer ID certificate is a type of distribution certificate you use to distribute your app outside the Mac App Store. Signing your macOS apps, plug-ins, and installer packages with a Developer ID certificate lets Gatekeeper verify that apps are not created by malware developers and haven't been tampered with since they were signed. Signed apps will launch on macOS when Gatekeeper is enabled. Developer ID certificates are issued only to members of the Apple Developer Program or Apple Developer Enterprise Program.
There are two types of Developer ID certificates: a Developer ID Application is used to sign apps, and a Developer ID Installer is used to sign installer packages.