1In one sentence
ChatGPT is one helper you can reach from several doors: the website, an app on your computer, an app on your phone, and a small add-on inside your web browser.
2New words
- App — a program you install on your computer or phone, with its own icon.
- Desktop app — the ChatGPT app for Mac and Windows. Since July 2026 it holds three views in one window: Chat, Work and Codex. In late 2026 OpenAI is merging Chat and Work into one place (some users get it first); Codex stays separate but shares the same usage allowance.
- Browser extension — a small add-on inside the Chrome browser that opens ChatGPT in a side panel next to the web page you are reading. It is not available to everyone yet; it depends on your plan and country.
- Atlas — a separate web browser OpenAI launched in 2025 and shut down on August 9, 2026. If you read about it, know that it is gone; its ideas moved into the desktop app and the extension.
- Account — your login. One account works in every door, and your chats follow you. On the website and in the iPhone and Android apps you can stay signed in to two accounts (say, personal and work) and switch without logging out; each keeps its own chats, memory and settings.
3Why you would want it
Each door suits a different moment. On the phone you can talk out loud or send a photo. On the computer the app can work inside your own folders. In the browser extension, ChatGPT reads the page you have open. Knowing the doors means less copying and pasting.
| Door | Where | Best for | Needs |
|---|---|---|---|
| Website | chatgpt.com in any browser | Everything in this part | Any plan (an account is best) |
| Desktop app | Mac, Windows | Work mode on your own files, long jobs, Codex for coders | Any plan; Work is limited on Free and Go |
| Phone app | iPhone, Android | Voice, quick questions, photos | Any plan |
| Browser extension | Chrome | Asking about the page you are reading | Not on every plan or in every country yet; check the help pages |
4Try it now
- On your phone, install the ChatGPT app from the App Store or Google Play and sign in with the same email.
- On your computer, go to chatgpt.com/download, install the desktop app and sign in.
- Open the chat you started in Chapter 1.1 on the phone. It is there.
- Tap the microphone or the sound-wave icon in the phone app and say: Give me three ideas for dinner tonight.
5What you will see
The same conversation on both devices, with the chat list on the left (computer) or behind a menu button (phone). In the desktop app, a switch at the top offers Chat or Work; stay on Chat for now. If your app already shows them merged into one place, just type in the box.
6Watch out
- The desktop app's Work view can open your files and, if you allow it, control your computer. Say no to those requests until Chapter 1.15.
- Articles older than mid-2026 describe doors that no longer exist (Atlas, "agent mode", and Sora, OpenAI's video app, which closed in April 2026 and is fully shut down; use another video tool). Trust the menus in front of you over old screenshots.
7Go further
If the browser extension is offered to you, install it (make sure the maker is OpenAI; many look-alike extensions exist) and open any long article. Ask the side panel: Summarize this page in 5 points. Then read Chapter 1.3 to learn what is free.