How Google Gemini works: a plain-English guide for marketers

#01What does "Gemini" actually mean?

Google uses one name for several things. That causes confusion in meetings, so agree on terms first.

There are also standalone products with Gemini branding, such as Gemini Notebook (renamed from NotebookLM on 16 July 2026) and Gemini in Chrome.

#02Which models power which surface?

The model you get depends on your plan and the surface. These are the models marketers will meet in November 2026.

Our view: don't over-think the picker. Use the default for drafting. Switch to Argon when a task needs long documents, careful reasoning or many steps, such as a 40-page analyst report or a pricing comparison across four competitors.

#03How does the Gemini app build an answer?

A simplified picture of a single turn in the app:

1. Your prompt and context. This includes your message, any files, your custom instructions, and active skills (the feature replacing Gems, covered in lesson 5).
2. Connected apps. If you've allowed it, Gemini can read Gmail, Drive, Calendar and more than 40 third-party apps you connect under Customize.
3. Grounding in Google Search. For questions about the world, Gemini may search Google and use the results. Google calls this grounding. It's the reason the app can cite current pages.
4. Generation. The model writes the answer, sometimes with source links you can open.

Grounding is what links the app to your website. Google's crawler documentation says the Google-Extended robots.txt token controls whether your content may be used for grounding in Gemini Apps and for training future Gemini models. It does not affect Google Search. Lesson 14 covers that decision.

#04How are AI Overviews and AI Mode different from the app?

Both are features of Google Search, not of the Gemini app. Google Search Central describes them like this:

Google also says AI Mode and AI Overviews "may use different models and techniques", so the links they show will differ. That's why the track tests all three surfaces separately.

#05What can marketers use Gemini for?

#06What about data and privacy?

This is the question legal will ask first.

• Workspace business accounts. Google's Workspace pricing page says that when you chat with AI in Gemini, "your company data is not used to train models". Admins control which Gemini features are on.
• Personal accounts. Gemini Apps have their own activity settings. Google's Gemini Apps Privacy Hub explains what's kept, what human reviewers may see, and how temporary chats work. Read it before anyone pastes client data into a personal account.
• The API. On the Gemini API pricing page, Google marks whether data is "used to improve our products". It's "Yes" on the free tier and "No" on the paid tier for most models. Use a paid project for anything confidential.

Our view: write a one-paragraph rule. Client and customer data goes only into Workspace or a paid API project. Personal accounts are for public research only.

#07Worked example: Ledgerline

Ledgerline is a fictional accounts-payable software company. Details are illustrative.

Ledgerline's CMO asked a simple question in a planning meeting: "Are we using Gemini, and do we show up in it?" Three people gave three different answers, because each meant a different surface.

Walkthrough

1. The marketing ops lead listed the surfaces in the table above and named an owner for each.
2. The team agreed the data rule: no customer invoices or contracts in personal accounts.
3. The content lead ran ten buyer questions across the app, AI Mode and a normal search, and saved screenshots as a dated baseline.
4. The team noticed that AI Mode named Competitor B more often and linked to B's comparison pages. That became the starting hypothesis for lessons 13-16.
5. Training was booked for Workspace features first, since they needed no new spend.

#08Common mistakes

• Treating Gemini, AI Mode and AI Overviews as one channel. They have different controls and different measurement.
• Judging the product by the free model. The free app uses Flash-Lite, which is not the model your boss saw in a demo.
• Pasting client data into personal accounts.
• Blocking Google-Extended and expecting AI Overviews to change. It doesn't control Search features.
• Testing once. AI answers vary, so test the same questions repeatedly over time.

#09Try it yourself

Pick three buyer questions. Ask each in the Gemini app, in AI Mode and in a normal Google search. For each answer, note which brands are named, which pages are linked, and whether your site appears. Save the results in a dated sheet. You'll reuse it in lesson 20.

#10Quick quiz

1. Which robots.txt token controls grounding in Gemini Apps?

Answer: Google-Extended.

2. Does Google-Extended affect AI Overviews or AI Mode?

Answer: No. Those are Search features, governed by Googlebot, snippet controls and the Search generative AI setting.

3. Which model does the free Gemini app use?

Answer: A Flash-Lite model. AI Plus gets Flash, and AI Pro and Ultra get Gemini 4 Argon, Pro and Flash.

#11What should you check before the next lesson?

• You know which surfaces your team uses and who owns each one.
• You have a written rule on which data may go into which account.
• You have a dated baseline of three or more buyer questions across the three surfaces.

Previous: none, this is lesson 1. Next: Gemini plans and pricing for marketing teams. Or return to the Gemini for Marketers track. Related: How Gemini search results differ, AI Mode vs Gemini, Grounding, How Google picks sources.

#12Common questions

Is Gemini the same thing as AI Mode? No. Both use Gemini models and Google Search data, but the Gemini app is an assistant and AI Mode is a Search feature. They can give different answers and link to different pages.

Which Gemini model should marketers use? For everyday drafting and research, the default Flash model is fast and capable. Use Gemini 4 Argon, on AI Pro or Ultra, for complex analysis, long documents and multi-step work.

Does Gemini use my company data for training? Google says Workspace business data used with Gemini is not used to train models. Personal accounts have different activity settings, so read the Gemini Apps privacy hub before you paste client data.