ChatGPT.
Four modes.

Use Health to review information you choose to connect, such as supported medical records or Apple Health, and prepare better questions for a clinician. OpenAI says Health is rolling out to eligible U.S. users aged 18 or older on web and iOS; connecting Apple Health requires an iPhone. If you do not see Health, it may not be available on your account.

Review permissions before connecting data. Health can help you understand trends; it is not a diagnosis or treatment service. For urgent symptoms, use appropriate emergency care.

The model picker may show a reasoning or thinking level. Use a higher level for a genuinely difficult comparison, multi-step problem, or decision with tradeoffs. Use a faster setting for routine rewriting or a simple summary. The exact controls depend on your plan and interface. Merely typing “think harder” does not necessarily switch the selected level.

More reasoning does not replace missing facts. Attach the relevant document or provide the real numbers first. Check critical conclusions independently.

Start a new chat and select Temporary if you do not want the conversation to appear in your history or create new memories. OpenAI says an unsaved Temporary Chat is not used to improve models and may be retained for up to 30 days for safety. A personalized Temporary Chat can still use existing memory, custom instructions, and plugins; select the non-personalized option when available if you want those excluded. If you save the chat, it becomes a regular chat.

Try it for: a one-off question you do not need to revisit. Avoid adding secrets or third-party personal information merely because the chat is temporary. If you use a connected app or GPT action, the third party may have its own data practices.

Study mode asks questions, explains concepts in steps, and can quiz you. OpenAI says it is available across ChatGPT plans on web, iOS, and Android. In a regular chat, select Study from the + menu; on web you can also type @study. Study is currently unavailable inside Temporary Chats, GPTs, and Projects.

Upload your own notes if available and tell Study which pages to use. Verify facts against your course materials, especially for graded or high-stakes work.

• Personal health trend or records: Health, if your account is eligible.
• Complex decision or calculation: a higher thinking level, with real inputs.
• One-off conversation you do not want in history: Temporary Chat.
• A concept you want to understand and practice: Study.

For an ordinary writing task, a regular chat with a clear prompt is enough. These features do not make an answer automatically correct, private in every possible sense, or available on every plan.

1. Give the source: Upload notes, data, or the relevant excerpt so the answer has an evidence base.
2. Specify the output: Ask for a checklist, comparison, quiz, or question list rather than “tell me everything.”
3. Ask what is uncertain: Request a short list of assumptions and what would verify them.