What does iOS stand for? The name is generally read as iPhone Operating System. It is the core software made by Apple that runs the iPhone: the home screen, settings, the keyboard, notifications and the system that lets apps work at all. When your phone asks you to install an iOS update, it is offering a new version of that software.
Apple itself rarely spells the letters out. The system launched with the first iPhone under the plain name iPhone OS, and in 2010 Apple shortened it to iOS. Since then, the name has been treated as a brand of its own rather than an abbreviation to expand.
Quick facts
Stands for
iPhone Operating System (originally iPhone OS)Type
Brand name built from a short formHow to say it
"eye oh ess"Made by
AppleRuns on
iPhoneCapitals
Lowercase i, capital O and SNot to be confused with
ISO, a standards body, and IOS for network routers
What does iOS stand for, piece by piece?
| Part | Stands for | What it means |
|---|---|---|
| i | iPhone (and the i family of names) | Ties the system to the device |
| O | Operating | The layer that runs everything else |
| S | System | The full set of core software |
An operating system, often shortened to OS, is the base software on any computer or phone. It manages the screen, the battery, storage, the network and the apps. A laptop has one, a smart TV has one, and so does a phone. iOS is simply the one Apple builds for the iPhone.
Why the small i?
The lowercase i came before the phone. When Apple introduced the iMac, it said the i stood for internet, along with ideas like individual, instruct, inform and inspire. The letter later spread across the product line. The i in iPhone page tells that part of the story in more detail.
So iOS carries a double link: the i points back to iPhone, and through iPhone back to that early internet idea. That is why the name is written with a small i and a capital O and S. Writing IOS or Ios is a common slip.
iOS stands for the system, not the phone
People sometimes use iOS and iPhone as if they were the same thing. They are not. The iPhone is the hardware you hold. iOS is the software running inside it. The same phone can move from one iOS version to the next through free updates, gaining new features without any change to the device.
On a settings screen: "A new version of iOS is available. Your iPhone will restart to finish installing." Here iOS names the software, and the version number on the screen shows which release you are getting.
When an app listing says it "requires iOS" followed by a version number "or later," it means the phone's software must be at least that version, not that you need a newer phone.
Where else you see the name
- App pages: "Available for iOS" means there is a version for iPhone.
- Job ads: an "iOS developer" builds apps for Apple phones.
- Help guides: steps often say "On iOS, tap Settings" to separate them from steps for other phone systems.
- School and work forms: a device question may ask, "Which system does your phone use?" with iOS as one choice.
Apple's tablets once ran iOS too, before their version branched off with a name of its own.
Look-alikes: ISO, IOS and OS
ISO is the International Organization for Standardization, the group behind many world standards, and also a camera setting for light sensitivity. IOS in all capitals has been used for networking software on routers, where it stands for Internetwork Operating System. OS alone means any operating system.
Check the capitals and the setting. A phone, an app or a software update points to iOS. A network closet points to IOS. A camera menu points to ISO. The tech acronyms section has more letters from phones and computers, including UI and GUI.
Saying iOS out loud
Say the three letters: "eye oh ess." Nobody pronounces it like a single word. In writing, keep the lowercase i even at the start of a sentence, though some editors reword the sentence to avoid starting with it. Because the first sound is "eye," use "an" before it: "an iOS update," "an iOS app."
Questions people ask
What does iOS stand for on iPhone?
It stands for iPhone Operating System. The software was first called iPhone OS, and Apple shortened the name to iOS.
Is iOS the same as iPhone?
No. The iPhone is the physical phone, and iOS is the software that runs on it. Updating iOS changes the software, not the device.
Why is the i in iOS lowercase?
It follows Apple's naming style, which began with the iMac and continued with the iPhone. The i was linked to the internet and to words like individual and inspire.
How do you pronounce iOS?
Say "eye oh ess," one letter at a time. Each letter gets its own sound.
Is it a iOS or an iOS app?
Use "an iOS app," because the name begins with the vowel sound "eye."