# Feature Flag Introduction

![](/files/1Is6bWVPRguoBUGBu7V6)

When you deploy code to the production environment, the associated feature immediately becomes visible to users.\
The moment developers are perhaps most nervous is the moment of deployment. This is because even after sufficient testing, or sometimes even with testing, unexpected issues can arise.

Using Feature Flags, you can separate deployment from release to manage the entire lifecycle of a feature.

* You can test features in the production environment by keeping them accessible only to designated individuals before showing them to all users.
* After deployment, you can activate or deactivate features whenever you choose.

## Who needs Feature Flags?

Feature Flags are most recommended for developers, but they are not for developers only.

* Product managers/PM/PO who want to release features gradually
* QA teams who want to test in a specific environment before feature release
* System administrators who want to manage and control system functionality by toggling specific features on and off

And many other roles can make broad use of them.

## Feature Flag Use Cases

### Release Management

When applying and deploying multiple changes, you can reduce deployment complexity. By introducing a Feature Flag for each feature or service and starting deployment with it in the off state, you can focus on deployment without affecting other features, services, or the production environment. After deployment is complete, you switch Feature Flags to the on state one by one and monitor.

The advantages of this approach are:

* Since only some features can be released first, you can gauge the impact within a low risk level.
* Since only some features can be released first, internal testing is more manageable.
* You do not need to coordinate deployment timing across individual feature or service owners, allowing for flexible time management.

### Gradual Rollout

You can release a feature to specific users first before releasing to all users. Specific users can include QA, beta testers, and others. Alternatively, you can start with a small percentage of unspecified users and gradually release the feature to all users over time.

The advantages of this approach are:

* Since the feature is released to some users first, you can gauge the impact within a low risk level.
* You can receive user feedback and make changes if necessary.
* If an issue arises with the feature, you can immediately deactivate it.

### System Stability Management

You can maintain system stability by toggling features on and off without code deployment.

* When traffic spikes, you can block traffic to maintain server stability.
* To migrate to new servers or databases, you can control traffic between the existing and new servers.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.hackle.io/en/feature-flag/feature-flags.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.