Adoptable storage
Also known as: SD card as internal storage, adopted storage, format SD card as internal
Adoptable storage is an Android feature that formats a microSD card to act as internal storage. The card is encrypted and tied to that one device, so it stops being portable and cannot be read elsewhere.
- Formats an SD card to act as internal storage
- Encrypted and locked to one device — no longer portable
- Added in Android 6.0; disabled on Samsung Galaxy phones
Internal vs portable
Introduced in Android 6.0 (Marshmallow), adoptable storage lets the system treat an SD card like built-in storage — apps and their data can live on it, and it counts toward the phone’s internal capacity.
The trade-off is portability. When you adopt a card it is reformatted and encrypted to that single device, so you cannot pop it out and read it on a computer or another phone. The alternative is portable storage, where the card stays readable everywhere.
Limited availability
Not every phone offers it. Samsung has disabled adoptable storage on Galaxy devices since the Galaxy S7, citing performance, and several other makers skip it too. Where it exists, you enable it during card setup in Settings > Storage.
Because the card is encrypted to the device, removing or wiping that phone can leave the data unrecoverable, so it suits a card you intend to keep permanently inside one device.