---
title: 'Human in the loop (HITL)'
description: 'An operating pattern in which a human participates directly in the decision or execution path before work can continue.'
canonical_url: 'https://darkfactory.dev/glossary/human-in-the-loop'
markdown_url: 'https://darkfactory.dev/glossary/human-in-the-loop.md'
collection: glossary
date_published: '2026-08-03T00:00:00-04:00'
date_modified: '2026-08-26T00:00:00-04:00'
---

# Human in the loop (HITL)


## Definition

Human in the loop, or HITL, is an operating pattern in which a person must participate in the decision or execution path before work can continue. The human might supply missing judgment, approve a proposed action, correct an output, or perform a step the system is not authorized to take.

The presence of a click does not make oversight meaningful. The reviewer needs enough information, time, expertise, and authority to detect a problem and refuse the action. If volume or interface design turns approval into a reflex, the human becomes a procedural gate rather than an independent control.

Use HITL where the decision is consequential, difficult to verify automatically, or depends on accountable human judgment. Define what the reviewer sees, what they must decide, what happens after rejection, and how review quality is measured.

## Distinguish it from nearby terms

Human in the loop requires active participation before a transition. Human on the loop supervises actions that can proceed without prior approval. Human out of the loop has no routine person in the scoped action path.

## Check your understanding

A reviewer receives 600 agent changes per hour with a green "recommended" button and no diff. The workflow contains a required human click, but it does not provide the conditions for meaningful review.

## Also called

HITL

## Related factory areas

- [Human roles, organization, expertise & cognitive health](https://darkfactory.dev/factory/human-roles-expertise)

## Evidence and further reading

- [OpenAI: A Practical Guide to Building Agents](https://openai.com/business/guides-and-resources/a-practical-guide-to-building-ai-agents/)
- [Collaborator or Assistant: Work Partitioning](https://arxiv.org/abs/2605.08017)