> For the complete documentation index, see [llms.txt](https://developer.harness.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.harness.io/security-testing-orchestration/3.0/new-to-sto/key-concepts.md).

# Key Concepts

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[Targets, baselines, and variants](/security-testing-orchestration/3.0/new-to-sto/key-concepts/targets-and-baselines.md)
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[Severity scores and levels](/security-testing-orchestration/3.0/new-to-sto/key-concepts/severities.md)
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[Scan output variables](/security-testing-orchestration/3.0/new-to-sto/key-concepts/output-variables.md)
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[Fail pipelines based on scan results](/security-testing-orchestration/3.0/new-to-sto/key-concepts/fail-pipelines-by-severity.md)
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[Exemptions for specific issues](/security-testing-orchestration/3.0/new-to-sto/key-concepts/exemptions.md)
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[STO scan modes](/security-testing-orchestration/3.0/new-to-sto/key-concepts/sto-workflows-overview.md)
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[Orchestration mode](/security-testing-orchestration/3.0/new-to-sto/key-concepts/run-an-orchestrated-scan-in-sto.md)
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[Ingestion mode](/security-testing-orchestration/3.0/new-to-sto/key-concepts/ingest-scan-results-into-an-sto-pipeline.md)
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[Extraction mode](/security-testing-orchestration/3.0/new-to-sto/key-concepts/extraction-scans.md)
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