> ## Documentation Index > Fetch the complete documentation index at: https://agent-contracts.relari.ai/llms.txt > Use this file to discover all available pages before exploring further. # Core Concepts > Understanding the key concepts of Agent Contracts ## Core Primitives Concept Tree Light Concept Tree Dark **Specification**: A collection of scenario-specific requirements that defines the expected behavior of the agent application. * **Scenario**: A specific use case that the agent application is expected to handle. * **Contract**: A group of requirements that are expected to be met for a given scenario. * **Pre-condition**: A requirement that must be true **before** the execution. * **Path-condition**: A requirement that must be true **during** the execution. * **Post-condition**: A requirement that must be true **after** the execution. ## Ways to use Contracts Use Contracts Light Use Contracts Dark **Verification**: The process of checking **offline** if an agent application satisfies the contract requirements for each pre-defined scenario in the specification. **Certification**: The process of checking **in runtime** if an agent satisfies the **online contract requirements**.