AI Vocabulary · 08 Rules & Responsibility

What is AI System?

The EU AI Act's core legal term: a machine-based system that infers from its input how to produce outputs such as content, recommendations or decisions.

Intermediate

Whether the EU AI Act applies to something starts with one question: is it an AI system? Article 3 defines it by a few features. It is machine-based, designed to operate with varying levels of autonomy, and may adapt after it is put into use. For explicit or implicit objectives, it infers from the input it receives how to generate outputs, such as predictions, content, recommendations or decisions, that can influence physical or virtual environments.

The key word is "infers". Software that only follows rules written entirely by people is generally not an AI system. A chatbot, a CV screening tool or an image generator generally is.

An AI system is not the same as an AI model. A model such as a large language model becomes part of a system when it is built into an application with an interface, data and a purpose. The Act has separate rules for general-purpose AI models.

The European Commission published guidelines on the definition in February 2025. They are not binding, but they help with borderline cases.

Why it matters for you

The definition decides whether the Act applies at all, and then your role as provider or deployer decides which duties you have. Most tools you use at work count as AI systems.

Own it

List the AI systems in your company: what each one does, who supplies it and who uses it. That overview is the basis for every further step. This entry is an overview, not legal advice.

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