Internal storage
Also known as: built-in storage, device storage, onboard storage, phone internal memory
Internal storage is the built-in, non-removable flash memory soldered inside a phone or tablet, where the operating system, apps, and your files live. Its size is fixed at purchase (for example 128 GB), and it is what fills up — not RAM and not a memory card.
- Built-in, non-removable flash memory in the device
- Fixed at purchase; holds the OS, apps, and files
- Usable space is less than the advertised capacity
What internal storage holds
Internal storage is the device’s permanent space: the OS, every installed app, and your photos, videos, downloads, and app data all share it. Unlike a memory card, it cannot be removed or swapped, so the capacity you buy is the capacity you keep for the life of the device.
The usable amount is always less than the number on the box. The operating system and preinstalled apps occupy several gigabytes, and drives are measured in a way that reports slightly less than the advertised figure — so a “128 GB” phone shows under 128 GB free when new.
Internal storage vs card vs RAM
On Android with a card slot, internal storage is the built-in space and the memory card is removable extra space; you can often move media or some apps to the card to relieve a full device. RAM is different again — temporary working memory that runs apps, not a place files are saved.
When a phone warns it is “out of space,” it means internal storage, not RAM. You free it by removing photos, videos, large downloads, and caches, or by offloading data to a card or the cloud. On Android, Settings > Storage breaks down what is using it.