Reference
Glossary
Answer in brief
Plain-English definitions of the phone terms used across this site, from mAh and telephoto lenses to cover screens and Qi2.
Updated . US launch prices; check before you buy.
Terms
- Foldable phone
- A phone with a flexible screen that folds in half. Book-style foldables like the iPhone Duo and Galaxy Z Fold 8 open into a small tablet.
- Cover screen
- The outer screen on a foldable, used when the phone is closed. The iPhone Duo's is 5.4 inches.
- Crease
- The faint line where a foldable screen bends. Reviewers judge foldables partly on how visible it is.
- mAh
- Milliamp-hours, a measure of battery capacity. Bigger usually means longer battery life, but software and chip efficiency matter as much.
- Battery test
- A repeatable test that runs a phone until it dies, such as Tom's Guide's web-browsing test or PCMag's streaming test. Results are only comparable within the same test.
- Telephoto lens
- A camera lens for optical zoom. Phones without one, like the iPhone 17 and iPhone Duo, zoom by cropping, which loses detail.
- Variable aperture
- A camera that can change how much light it lets in, giving more control over depth of field. New on the iPhone 18 Pro and Pro Max.
- ProRAW and ProRes
- Apple's professional photo and video formats, which keep more data for editing. Not available on the iPhone Duo.
- eSIM
- A digital SIM built into the phone instead of a removable card. Some iPhones are eSIM-only.
- Qi2
- The magnetic wireless charging standard, compatible with MagSafe accessories. The OnePlus 15 lacks it.
- Tensor
- Google's own chip used in Pixel phones. The Pixel 11 uses the Tensor G6.
- A20 Pro
- Apple's chip in the iPhone Duo.
- S Pen
- Samsung's stylus, built into the Galaxy S26 Ultra.
- Privacy display
- A Galaxy S26 Ultra feature that dims the screen at side angles so people next to you can't read it.
- Software update support
- How many years a phone gets Android or iOS updates and security patches. The Pixel 10a gets 7 years.
- Touch ID
- Apple's fingerprint sensor. The iPhone Duo uses Touch ID instead of Face ID.
Cite this entry
What Is the Best Phone. “Phone Buying Glossary: Terms Explained.” whatisthebestphone.com, updated November 11, 2026. https://whatisthebestphone.com/glossary