Key Definitions

Article 3 of the AI Act contains 68 legal definitions that form the interpretive foundation of the entire regulation. Mastering these definitions is essential—the difference between compliance and violation often turns on precise definitional analysis.

The AI System Definition (Article 3(1))

The definition of "AI system" is the most consequential in the regulation:

'AI system' means a machine-based system designed to operate with varying levels of autonomy, that may exhibit adaptiveness after deployment and that, for explicit or implicit objectives, infers, from the input it receives, how to generate outputs such as predictions, content, recommendations, or decisions that can influence physical or virtual environments.

Breaking Down the Definition

What IS and IS NOT an AI System

Likely AI Systems:

• Machine learning models (supervised, unsupervised, reinforcement)
• Large language models and generative AI
• Computer vision systems
• Recommendation engines using ML
• Autonomous decision-making systems
• Predictive analytics using inference

Likely NOT AI Systems:

• Simple rule-based expert systems (no inference)
• Basic statistical analysis
• Traditional database queries
• Deterministic algorithms
• Conventional software without inference capability

Actor Definitions: The AI Value Chain

Provider (Article 3(3))

'Provider' means a natural or legal person, public authority, agency or other body that develops an AI system or a general-purpose AI model or that has an AI system or a general-purpose AI model developed and places it on the market or puts the AI system into service under its own name or trademark, whether for payment or free of charge.

Key Elements:

• Develops OR has developed (covers outsourced development)
• Places on market OR puts into service
• Under own name or trademark (takes responsibility)
• Regardless of payment (free AI included)

Provider Triggers:

• You build AI and sell/deploy it under your brand
• You commission AI development and release it as your product
• You significantly modify another's AI and rebrand it

Deployer (Article 3(4))

'Deployer' means a natural or legal person, public authority, agency or other body using an AI system under its authority, except where the AI system is used in the course of a personal non-professional activity.

Key Elements:

• Uses AI "under its authority" (operational control)
• Excludes personal/non-professional use
• Includes internal business use
• Does not require market placement

Deployer Examples:

• Company using AI for HR decisions
• Bank using AI for credit scoring
• Hospital using AI diagnostic tool
• Retailer using AI for pricing

Importer (Article 3(6))

'Importer' means a natural or legal person located or established in the Union that places on the market an AI system that bears the name or trademark of a natural or legal person established in a third country.

Key Elements:

• Must be EU-established
• Brings non-EU AI to EU market
• AI bears third-country provider's name

Distributor (Article 3(7))

'Distributor' means a natural or legal person in the supply chain, other than the provider or the importer, that makes an AI system available on the Union market.

Key Elements:

• In supply chain but not provider/importer
• Makes AI available (resellers, marketplaces)

Authorised Representative (Article 3(5))

'Authorised representative' means a natural or legal person located or established in the Union who has received and accepted a written mandate from a provider of an AI system or a general-purpose AI model to, respectively, perform and carry out on its behalf the obligations and procedures established by this Regulation.

Purpose: Enables non-EU providers to fulfill EU obligations

Critical Lifecycle Definitions

Placing on the Market (Article 3(9))

The first making available of an AI system or a general-purpose AI model on the Union market.

Triggered by: First commercial availability in the EU Significance: Triggers most provider obligations

Putting into Service (Article 3(11))

The supply of an AI system for first use directly to the deployer or for own use in the Union for its intended purpose.

Triggered by: First operational use for intended purpose Significance: Alternative trigger for obligations; relevant for internal deployments

Substantial Modification (Article 3(23))

A change to an AI system after its placing on the market or putting into service which is not foreseen or planned in the initial conformity assessment carried out by the provider and as a result of which the compliance of the AI system with the requirements set out in Chapter III, Section 2 is affected or the intended purpose for which the AI system has been assessed is modified.

Substantial Modification Triggers:

• Change affects compliance with requirements
• Change modifies assessed intended purpose
• Change was not foreseen in original conformity assessment

❗ Important: A substantial modification can convert a deployer into a provider, triggering full provider obligations for the modified system.

Purpose and Misuse Definitions

Intended Purpose (Article 3(12))

The use for which an AI system is intended by the provider, including the specific context and conditions of use, as specified in the information supplied by the provider in the instructions for use, promotional or sales materials and statements, as well as in the technical documentation.

Compliance Implication: Provider obligations are assessed against intended purpose

Reasonably Foreseeable Misuse (Article 3(13))

The use of an AI system in a way that is not in accordance with its intended purpose, but which may result from reasonably foreseeable human behaviour or interaction with other systems, including other AI systems.

Compliance Implication: Risk management must address foreseeable misuse, not just intended use

Definitions Quick Reference