application/vnd.android.package-archive

The Android app installer: compiled code, resources and a manifest in a signed zip, which is also all a byte sniffer will ever see — PK at the start, no APK-specific signature, with the AndroidManifest.xml entry and the signing block doing the real identification. The type matters at serve time because Android historically refused to install sideloaded packages delivered under application/octet-stream, the default of any server that never mapped .apk. Despite the vnd. tree name it never completed IANA registration; it is a de facto label the whole ecosystem honors anyway.

.aab app bundles are the Play Store upload format, not this type — stores repackage them into APKs for delivery.

Defined by Android application fundamentals. Registry facts from the IANA media-types registry via mime-db.