Decoder. plain-English AI glossary

Synthetic data

▲ Rising

Training data made by a model rather than collected from the real world.

Think of it like

Like a flight simulator generating endless practice scenarios so pilots don’t need a real storm to train on.

Example

A strong model writes thousands of math problems with worked solutions, and those become training data for a smaller model.

How it actually works

Synthetic data lets teams manufacture examples where real data is scarce, private, or expensive, and to target specific weaknesses. Used well, it boosts capability cheaply; used carelessly, it risks model collapse — training on a model’s own averaged output can erode diversity and amplify its errors over generations. Quality control and grounding in real data are the guardrails.

For product teams

A powerful way to cover gaps and rare cases — but data made by models can quietly inbreed if you’re not careful.

For engineers

Model-generated training examples; scalable but risks distribution collapse without real-data anchoring/filtering.

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