# AI training data

URL: https://sellmydatatoai.net/glossary/ai-training-data

AI training data is the text, code, images, audio, video or interaction records used to teach a machine learning model, adjust its behavior or test it.

AI training data is any collection of examples that a machine learning model learns from or is measured against. For large language models it is used for pre-training on large text and code corpora, for fine-tuning on curated sets and for evaluation.

## What training data do AI companies pay for?

The training data AI companies pay for is mostly data they cannot collect from the open web. [DataVendor](https://datavendor.ai/blog/ai-training-data-marketplaces), a marketplace run by HUD, says labs pay more for human-written code, complex products and systems languages such as Rust, Go, C and C++. Internal communications with linked context, [evaluation datasets](https://sellmydatatoai.net/glossary/evaluation-dataset) and [agent trajectories](https://sellmydatatoai.net/glossary/agent-trajectory) are also in demand.

Public data, scraped data and contact lists rarely sell, because buyers can already get them or cannot clear the rights. The guide to [what data AI companies buy](https://sellmydatatoai.net/guides/what-data-do-ai-companies-buy) has the full list.

## Is training on copyrighted data fair use in the US?

Training on copyrighted data is fair use in the US only case by case, under the four factors in [17 USC 107](https://www.law.cornell.edu/uscode/text/17/107). The [US Copyright Office's May 2025 report on generative AI training](https://www.copyright.gov/ai/Copyright-and-Artificial-Intelligence-Part-3-Generative-AI-Training-Report-Pre-Publication-Version.pdf) concluded that some training uses will qualify as fair use and some will not. A license removes that question for the licensed data.

## Who owns training data once it is licensed?

Training data stays owned by the seller under most [data licenses](https://sellmydatatoai.net/glossary/data-license), and the license decides whether the buyer's rights are exclusive, time-limited or perpetual. A [free data valuation](https://sellmydatatoai.net/data-valuation) gives a realistic range for your records.