CHAPTER 03 · DATA AND COMPUTERS

Training a model versus using it

An important distinction: a model is first built, then put to use.

What is it?

A model is first trained on large amounts of data (pre-training) and may then be adapted for particular tasks. Using it is called inference: the model computes an answer, and its parameters usually do not change in the process.

An everyday example

When you tell a chatbot your name and it uses it in the next reply, the name is stored in the conversation or a separate memory feature, not in the trained model.

Why does it matter?

The distinction explains why a model does not know the latest events, how an application can still look up fresh information, and what happens to what you type in.

A common misconception

That a model learns from every conversation as it goes. Whether your data are ever used for training depends on the provider and your settings.

In more detail

What is pre-training?

The model learns general patterns from a huge number of examples. For language models, a common task is predicting the next token.

What is fine-tuning?

A model can be trained further for a particular task, language or style of answering.

Does it learn from every answer?

Usually not, in the sense of permanently changing its parameters. But the app may store data, use a memory feature or allow later training.

What is inference?

The process in which an already-trained model produces output from the current input.

Remember: “I’ll remember that” in a chat does not necessarily mean the model’s parameters have changed.

Reliable sources

Last reviewed 1 November 2026. An explainer, not professional, legal or medical advice. For rules and figures that change, check the official version.