Explainer
Large language model (LLM).
A large language model – LLM for short – is the “brain” behind ChatGPT, Claude, Gemini and business AI agents. It can understand text and write new text. But on its own it does nothing until you connect it to a task and to data.
In short
- An LLM has learned from a huge amount of text and can both understand and produce language.
- It does not know your business – you have to give it your documents (for example through RAG).
- The model itself is only part of the solution; the value comes from the task, data and rules around it.
On this page
What it is, simply
A language model is a program that has learned, from a huge amount of text, how words and ideas follow on from one another. That is why it can read an email and understand that it is a complaint, summarise a long contract or write a clear reply.
“Large” means the model has billions of internal parameters and was trained on text from a large part of the internet, books and other sources. That is why it handles Czech, English, technical terms and different writing styles.
How it works (without the maths)
In essence, the model predicts which word should come next so that the answer makes sense. It does this so well that the result looks like understanding – and for practical work with text, it behaves that way too.
This leads to two important traits:
- It can sound confident even when it is not sure. When it lacks information, it may “fill in the gaps”. This is called hallucination.
- It does not know your business. It does not know your prices, rules or clients until you give them to it. That is what the RAG technique is for.
Well-known models
The best known include the GPT models from OpenAI (behind ChatGPT), Claude from Anthropic, Gemini from Google, Llama from Meta and Mistral from France. They differ in quality, price, speed, and where and how they process data.
For a business, a more important question than “which one is smartest” is where the data will be processed and under what contractual terms. More in AI and GDPR.
What it means for your business
The model on its own is like a talented graduate with no work experience. It can read and write, but it does not know how things work at your company. It only adds value once you:
- connect it to a specific task (sorting enquiries, checking invoices),
- give it your documents (price lists, internal policies, history),
- and set rules for what it may do on its own and what a person approves.
That is how an AI agent comes about.
Frequently asked questions
What does LLM stand for?
Large Language Model. It is a type of artificial intelligence that understands text and can produce it.
Do language models understand Czech?
Yes, today’s large models handle Czech very well, including technical terms. Quality varies between models, though, so it is worth testing them on your real texts.
Does the model learn from my data?
It depends on the service’s contractual terms. With the business and API versions from the major providers, customer data is usually not used for training, but you should always check this in the contract.
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