ChatGPT: the models, the apps and when to use which

What it is

ChatGPT is an AI assistant made by OpenAI. You type, speak or upload files, and it drafts, summarises, analyses or answers. Behind it sit several models (the trained systems that write the answers), and a Thinking setting that controls how long it reasons before replying.

Think of a dial on an oven rather than a choice of ovens: the same assistant, set to quick, medium or long, depending on the dish.

The table shows the current names, as of November 2026; check the maker's page, because names change often.

Free and Go users have a Think option for harder questions, powered by GPT-5.6 Luna.

Why it matters

• ChatGPT runs on the web, in desktop apps, on iOS and Android, and as a Chrome extension.
• Extensions work inside Excel, Word, PowerPoint and Google Sheets, with fuller access on paid plans.
• ChatGPT Work is OpenAI's tool for handing over longer, multi-step tasks; Codex is its coding tool. Both use their own models and limits.
• With GPT-6, answers can include visuals and interactive elements (OpenAI calls this Intelligent UI). Check the numbers behind any chart.
• Plans differ on data. On personal plans (Free, Go, Plus, Pro) your content can be used to train models unless you opt out. On Business, OpenAI states it won't train on your workspace's data; for Enterprise and its other business plans it states it does not train on your data by default.
• Like any assistant, ChatGPT can state wrong facts confidently, and features vary by plan; research results and actions it takes still need a person to check.

How to do it

1. Check which plan your organisation has approved, and sign in to the work workspace, not a personal account (see guide 10).
2. Start on Instant for everyday drafting; move to Medium or High for analysis and planning (see guide 03).
3. Create a project (a workspace holding files and standing instructions) for repeat work.
4. Use deep research for questions that need many sources (see guide 08) and open the key citations.
5. Connect approved apps (links to email, files or calendars) only with permission, and keep the setting that asks before ChatGPT acts (see guide 13 and guide 40).
6. Review every draft, figure and action before it is used or sent. You are the final check.

Example

Before: "Summarise this sales spreadsheet."

After: in the approved workspace, with made-up or cleared data, set to Medium:

Here is a sales table for [quarter] (test data).
1. Give total sales by region and the change from last quarter.
2. Show the formula or steps for each total.
3. Flag any row that looks like an error or outlier.
4. Write three plain-language bullets for a manager.
If a figure is missing, say so rather than guessing.

You then recalculate two totals yourself and check every flagged row before the bullets go into a report.

Common mistakes

• Using a personal account for work. Fix: use the approved Business or Enterprise workspace.
• Leaving the highest thinking level on for everything. Fix: use Instant for simple jobs; it is faster and saves your limit.
• Trusting charts because they look polished. Fix: ask for the underlying figures and check them.
• Giving connected apps permission to act freely. Fix: keep "always ask" or read-only until your team trusts the task.
• Assuming every feature is on your plan. Fix: some models, Work and extensions depend on plan and administrator settings.

Try it this week

1. Sign in to the approved workspace (2 minutes).
2. Create a project called "Practice" with a made-up one-page document and a one-line tone instruction (5 minutes).
3. Ask one analysis question on Instant, then on Medium, and compare the answers (5 minutes).
4. Write one line for your team: which setting for which job (3 minutes).

Going further

• Memory lets ChatGPT carry facts between chats; review it in settings and switch it off for sensitive work.
• Scheduled tasks run a prompt at a set time; review each output before acting on it.
• Custom GPTs and skills save instructions for repeat jobs (see guide 11).
• Voice and image creation are available with plan limits; check generated images before sharing.
• Business and Enterprise administrators can control which models and apps staff may use.

Key words

• Model: the trained system that reads your request and writes the answer.
• Thinking level: how long ChatGPT reasons before answering: Instant, Medium, High, Extra High or Pro.
• Project: a workspace with saved files and instructions for related chats.
• App (connector): an approved link that lets ChatGPT read or act in another tool.
• Workspace: the shared, administered business account your organisation controls.

Sources

Examples and figures in this guide are illustrative. AI tools change often: check what your organisation's approved tools offer today. Use approved tools only, and a person checks and decides.

Prefer to print or share it? Download this guide as a PDF (285 KB), or the complete AI Field Guide (2.5 MB).