Memory card (SD/microSD)
Also known as: SD card, microSD card, flash memory card, expandable storage
A memory card is a small, removable flash-storage card — full-size SD or the tiny microSD used in phones — that adds storage to a device or holds photos and video from a camera. Many Android phones accept one to expand space; most iPhones do not.
- Removable flash storage in SD and microSD sizes
- Common on Android; most iPhones have no card slot
- Speed class matters for 4K video and photo bursts
SD vs microSD and capacity classes
The two common sizes are full-size SD (cameras, laptops) and microSD (phones, action cameras, handhelds), with adapters bridging the two. Capacity tiers are labeled SDHC (up to 32 GB), SDXC (up to 2 TB), and SDUC (above that); a phone or camera only supports cards up to the tier it was built for.
Speed matters as much as size. Ratings like UHS Speed Class (U1, U3) and Video Speed Class (V30, V60) tell you whether a card can keep up with high-resolution photo bursts or 4K video without dropping frames.
Using a card to free phone space
On Android with a card slot, you can move photos, videos, and some apps to the card to reclaim internal storage. Insert the card, then in Settings > Storage choose to move media, or set the camera to save new shots to the card. Some phones offer adoptable storage to merge a card into internal space, which formats and locks the card to that device.
Cards are removable and can fail or corrupt, so treat them as convenient extra space rather than your only copy. Keep an independent backup of anything important, and eject or unmount a card before pulling it out.