The tools: which to use for what

One cheese, two texts

Lúcia has a small online shop selling products from São Jorge. She wants a short description for the cured cheese. She types exactly the same request into two different AI assistants.

One gives her a more poetic text, with the sea and cows in the pasture. The other gives her a more direct text, with three points: taste, curing, how to serve. Neither is wrong. They are different styles. Lúcia keeps the second and takes one sentence she liked from the first.

This is how you choose a tool: by trying it, on a task of your own.

The concept: several brands of the same kind of engine

All the assistants in this lesson use language models (lesson 1), which guess the next word. The assistant is the program you talk to; the model is the engine working inside it. What changes is the company that makes them, the style of the answers, the extras (internet search, images, voice) and the places where they appear.

It is like supermarkets. They sell almost the same things, but each one has its own layout, its own brands and its own opening hours. There is no "best" for everyone. There is the one that suits you.

The main ones, today

This is how it looks on 6 October 2026; your screen may differ.

All of them do the essentials: writing, summarising, explaining, giving ideas, translating. The last column says where each one is most at hand or what is particular about it.

Tool	Made by	Where you find it	Handy for…
ChatGPT	OpenAI (USA)	chatgpt.com and app	General use; it was the one that made this kind of assistant known, at the end of 2022. It has voice conversation and creates images.
Claude	Anthropic (USA)	claude.ai and app	General use; widely used for writing and for working on documents you send it.
Gemini	Google (USA)	gemini.google.com, app, Gmail and Android phones	People who already use Google accounts and programs.
Copilot	Microsoft (USA)	copilot.microsoft.com, Windows and, in some accounts, Word, Excel and Outlook	People who work on Windows and in Office.
Le Chat	Mistral AI (France)	chat.mistral.ai and app	General use; it is the alternative made by a European company.
Perplexity	Perplexity AI (USA)	perplexity.ai and app	Searching: it answers and shows where each part came from, with links to the sources.

Several of these can now search the internet. When they do, they show their sources. Open them.

Almost all of them have a free version and paid versions. To start, the free one is enough. Prices and differences between versions change a lot: see the Current state page.

The AI you already have, without installing anything

Often you do not even need to go to a website. The AI is already inside what you use:

• In email: Gmail can suggest replies and summarise long conversations, with Gemini. Outlook can do the same with Copilot. It depends on the account and the country.
• In Word and Excel: in some accounts, Copilot helps you write, summarise or do calculations.
• On the phone: many Android phones come with Gemini; the most recent iPhones come with Apple's AI features (it depends on the model and the language set). WhatsApp has an assistant from Meta, which appears as a coloured circle.

If you see a button with a star, some sparkles or the words "AI", it is almost always this.

How to choose: try two

You do not need an account with all of them. Do it like this:

1. Pick a real task of your own (an email, a summary, a description for your shop).
2. Type the same request into two assistants.
3. Compare them with three questions: did it understand what I wanted? Did it write in the language and style I asked for? Did I need many corrections?
4. Keep the one that gave you less work. In a few months, if you like, repeat the test.

Here is a request for the test:

Write a 60-word description to sell cured São Jorge cheese in a small online shop. Simple, honest tone, no exaggeration and no words like "incredible". In plain, natural English.