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Lesson 1 of 6 · 4 min read · Beginner

What AI chatbots can and cannot do

What an AI chatbot actually is, the handful of things it is reliably good at, and the three things it gets wrong often enough that you should know before you start.

In this lesson you will

  • Describe what a chatbot is doing when it answers you
  • Name three tasks it is good at and three where you should be careful

An AI chatbot is a program you type to in plain language. You write what you want, it writes back. ChatGPT, Claude and Gemini are the three most people have heard of, and all three have a free version. You will not need to pick one yet, and you will not need to pay for anything in this course.

How a large language model answers youYou pay for what goes in (input tokens) and what comes out (output tokens). Nothing is remembered between calls unless it is sent again.Your prompttext, files, imagestokenisedInput tokenscounted & billedThe modelpredicts the next tokenone token at a timeOutput tokenscounted & billedOutput tokens usually cost 3–5× more than input tokens. Long answers, not long questions, are what run up an API bill.
Figure 1.Your message goes in, the model predicts the most likely next word again and again, and the reply comes out. It is not looking anything up. It is continuing your text in the most plausible way it has learned.

The one idea worth keeping

The model does not know things the way a search engine or an encyclopaedia does. It has read an enormous amount of text and learned what usually comes next. That is why it is so good at writing, rephrasing and explaining, and why it can occasionally state something false in a confident, well-written sentence. Both come from the same place.

Where a chatbot helps, and where it needs a second look. Every item here is something you will do in this course.
TaskHow much to trust itWhy
Write or rewrite a message, email or noteHigh, read it once before sendingWriting is what it was trained on most
Explain something confusing in plain wordsHighIt is rephrasing, not inventing
Summarise text you paste inHigh, spot-check one detailEverything it needs is in front of it
Turn messy notes into a list or a planHighStructure is easy for it
Give you a fact, a date, a price or a statisticLow, check itIt may produce something plausible rather than true
Do arithmetic with several stepsMedium, check the numbersIt predicts text; it is not a calculator by default
Tell you about something that happened this weekLow unless it searched the webIts knowledge stops at a training date

Knowledge check

You ask a chatbot for the opening hours of a local shop and it answers confidently. What should you do?

Lesson FAQ

Do I need to create an account to start?

Not for this course. The Try it boxes run on this page. When you are ready to use a chatbot properly, ChatGPT, Claude and Gemini each have a free account that takes a minute to set up.

Is AI going to give me wrong answers?

Sometimes, and it will sound sure of itself when it does. That is why the course teaches you which tasks to trust it on (writing, explaining, summarising) and which to check (facts, numbers, anything recent).

Which chatbot is the best one for a beginner?

For your first 30 minutes it genuinely does not matter. They are more alike than different at this level. Lesson 6 points you to a short guide that picks one based on what you want to do.

Finished reading?

Mark it done to track your progress through the course.

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