Core concepts
Runs, spans, projects, versions and datasets, defined in one page.
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A short glossary you will use everywhere else in the docs.
Run and span
A run is one call to your agent. A span is one step inside it: a model call, a tool call or a guardrail check.
Project and version
A project is one agent. A version is a saved snapshot of its prompts, tools and settings.
Dataset and eval
A dataset is a list of cases. An eval scores a version against a dataset.