Have you ever wondered how ChatGPT seems to know everything? Sure, it sometimes gets things wrong. But other times, its knowledge can feel uncanny. Like it knows so much about you, the world, and everything that’s ever been written.
But despite its confident tone and the mountain of information it can draw from, ChatGPT doesn’t know everything. And it certainly can’t “think” in the same way you and I can – even though it may seem that way.
It’s also not a God or some higher being. I’m not quoting sci-fi here, there are an increasing number of reports about people having chatbot-induced delusions, and they could become more common the more we rely on AI.
That’s why it’s more important than ever to understand how tools like ChatGPT actually work, what their limitations are, and how to get the most out of them. So let’s take a look behind the scenes.
What is ChatGPT? And how does it work?
ChatGPT is a large language model (LLM) created by OpenAI. You can use it for free or pay for a subscription to access more advanced versions. These versions are known as models, and each one works a little differently – we’ve got a full explainer about ChatGPT model names here.
At its core, a large language model is a type of AI that’s trained to predict text. It generates responses by predicting which words are most likely to come next in a sentence – and it’s good at it.
That’s why ChatGPT can sound fluent, informed, and even witty. But it also doesn’t really “understand” what you’re saying. Sure, it understands language structure, but not the meaning or intent behind things in the same way a human would. This also explains why it sometimes gets things wrong or makes up facts entirely, which is known as hallucinating.
The simplest way to think about it is to imagine a really advanced autocomplete. You give it a prompt, and it fills in what it thinks should come next based on everything it’s seen before.
Where does ChatGPT’s knowledge come from?
So, how does ChatGPT “know” so much? It all comes down to training data.
ChatGPT was “trained” on an enormous amount of data, including books, articles, websites, code, Wikipedia pages, public Reddit threads, open-source papers and much, much more. The goal is to show it all of this information about the way humans write, explain, argue, joke, and connect ideas.
This means that ChatGPT has seen a wide range of language styles and subjects. But it hasn’t seen everything, and some ChatGPT models don’t go on the internet in real-time either – this is why you might have asked for information in the past, and it feels out of date.
Its knowledge is often limited to what it was trained o,n and in the case of some models, that training was frozen at a certain point. For example, that was June 2024 for GPT-4o. So it might not know the latest news or reflect newer cultural shifts. That said, some models do have browsing capabilities now, so it's worth checking which one you're using – this is usually displayed at the top of the screen in a drop-down menu.
So, training data is the foundation of what ChatGPT knows. But its answers are also shaped by what’s known as reinforcement learning, which means it also learns from human feedback about what makes a helpful or accurate response.
Did ChatGPT read all of the internet?
This is where things get a bit murky. Yes, some of the data used for training ChatGPT was collected by scraping publicly available content from the internet. That means tools like ChatGPT have “read” large parts of what’s online, including public forums, blog posts, and documentation. Basically anything that’s openly accessible and not blocked by the site or copyright laws.
Although the boundaries are blurry. AI companies have been criticized for using material like books from shadow libraries in their training data. Whether they should have used that content is part of ongoing debates and legal challenges around data ownership, consent, and ethics.
But even though what these models have been trained on isn’t always crystal clear, it’s safe to say that ChatGPT hasn’t read your private emails, personal documents, or secret databases. (At least, let’s hope not.)
An important thing to note here is that because ChatGPT has learned so much from human-made content, it can sometimes reflect the same biases, gaps, and flaws that already exist in our culture and online spaces.
How does ChatGPT decide what to say next?
When you type a question into ChatGPT, it breaks your prompt into smaller units, called tokens. It then uses everything it learned during its training to predict the next token. And the next one and the next one and the next one. Until a full answer appears.
This happens in real time, which is why the text often looks like it’s being typed live. It is, in a way. Each word is a prediction, based on everything that came before it.
This is also why some answers feel right but somehow weirdly… off. Because it’s remixing words, not reasoning. If you want to dig deeper, we’ve got a full guide about how ChatGPT knows what to say.
So why does it seem like ChatGPT knows everything?
If ChatGPT ever feels like it knows everything about you, that’s down to its memory features. It can store important things in long-term memory, and even remember things from all your past conversations.
It’s also incredibly good at sounding smart. Its responses often have the right structure, grammar, tone, and rhythm – because that’s what it’s been trained to mimic. So it creates the illusion that it always knows what it’s talking about. But this fluency isn’t the same as accuracy.
Often, it’s useful. Sometimes, it’s wrong. And sometimes, it’ll be confidently wrong, which is where things can get tricky if you’re not paying attention. Especially if you’re not aware of how good it is at sounding confident and hyping you up, too.
The goal here isn’t to scare you off AI tools altogether. It’s to help you use ChatGPT more wisely. ChatGPT is a brilliant tool for sparking ideas, writing drafts, summarizing text, and even helping you think more clearly. But it’s not magic, it’s not sentient. And, maybe most important of all, it’s not always right.
The more we understand what’s really going on behind the curtain, the more we can use AI tools like ChatGPT with intention and not fall for the illusion of intelligence.
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