> ## Documentation Index
> Fetch the complete documentation index at: https://docs2.growthbook.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Feature Flag Fundamentals

> Learn about the basics of feature flags.

export const CommercialFeature = ({feature, description}) => {
  const commercialFeatures = {
    "adv-presentations": {
      plan: "enterprise",
      displayName: "Adv Presentations"
    },
    "advanced-permissions": {
      plan: "pro",
      displayName: "Advanced Permissions"
    },
    "ai-byok": {
      plan: "enterprise",
      displayName: "Ai Byok"
    },
    "ai-suggestions": {
      plan: "enterprise",
      displayName: "AI Suggestions"
    },
    archetypes: {
      plan: "pro",
      displayName: "Archetypes"
    },
    "audit-logging": {
      plan: "enterprise",
      displayName: "Audit Logging"
    },
    "cloud-proxy": {
      plan: "pro",
      displayName: "Cloud Proxy"
    },
    "code-references": {
      plan: "pro",
      displayName: "Code References"
    },
    "contextual-bandits": {
      plan: "enterprise",
      displayName: "Contextual Bandits"
    },
    "custom-hooks": {
      plan: "enterprise",
      displayName: "Custom Hooks"
    },
    "custom-launch-checklist": {
      plan: "enterprise",
      displayName: "Custom Launch Checklist"
    },
    "custom-markdown": {
      plan: "enterprise",
      displayName: "Custom Markdown"
    },
    "custom-metadata": {
      plan: "enterprise",
      displayName: "Custom Metadata"
    },
    "custom-roles": {
      plan: "enterprise",
      displayName: "Custom Roles"
    },
    dashboards: {
      plan: "enterprise",
      displayName: "Dashboards"
    },
    "decision-framework": {
      plan: "pro",
      displayName: "Decision Framework"
    },
    "encrypt-features-endpoint": {
      plan: "pro",
      displayName: "Encrypt Features Endpoint"
    },
    "environment-inheritance": {
      plan: "enterprise",
      displayName: "Environment Inheritance"
    },
    "events-forwarder": {
      plan: "pro",
      displayName: "Events Forwarder"
    },
    "experiment-impact": {
      plan: "enterprise",
      displayName: "Experiment Impact"
    },
    "feature-configs": {
      plan: "enterprise",
      displayName: "Feature Configs"
    },
    "funnel-metrics": {
      plan: "pro",
      displayName: "Funnel Metrics"
    },
    "hash-secure-attributes": {
      plan: "pro",
      displayName: "Hash Secure Attributes"
    },
    "historical-power": {
      plan: "pro",
      displayName: "Historical Power"
    },
    holdouts: {
      plan: "enterprise",
      displayName: "Holdouts"
    },
    "incremental-refresh": {
      plan: "enterprise",
      displayName: "Incremental Refresh"
    },
    "json-validation": {
      plan: "enterprise",
      displayName: "JSON Validation"
    },
    "large-saved-groups": {
      plan: "enterprise",
      displayName: "Large Saved Groups"
    },
    learnings: {
      plan: "enterprise",
      displayName: "Learnings"
    },
    livechat: {
      plan: "pro",
      displayName: "Livechat"
    },
    "manage-official-resources": {
      plan: "enterprise",
      displayName: "Manage Official Resources"
    },
    "metric-correlations": {
      plan: "enterprise",
      displayName: "Metric Correlations"
    },
    "metric-effects": {
      plan: "enterprise",
      displayName: "Metric Effects"
    },
    "metric-groups": {
      plan: "enterprise",
      displayName: "Metric Groups"
    },
    "metric-populations": {
      plan: "pro",
      displayName: "Metric Populations"
    },
    "metric-slices": {
      plan: "enterprise",
      displayName: "Metric Slices"
    },
    "multi-armed-bandits": {
      plan: "pro",
      displayName: "Multi Armed Bandits"
    },
    "multi-metric-queries": {
      plan: "enterprise",
      displayName: "Multi Metric Queries"
    },
    "multi-org": {
      plan: "enterprise",
      displayName: "Multi Org"
    },
    "multiple-sdk-webhooks": {
      plan: "pro",
      displayName: "Multiple Sdk Webhooks"
    },
    "no-access-role": {
      plan: "enterprise",
      displayName: "No Access Role"
    },
    "override-metrics": {
      plan: "pro",
      displayName: "Override Metrics"
    },
    "pipeline-mode": {
      plan: "enterprise",
      displayName: "Pipeline Mode"
    },
    "post-stratification": {
      plan: "enterprise",
      displayName: "Post Stratification"
    },
    "precomputed-dimensions": {
      plan: "pro",
      displayName: "Precomputed Dimensions"
    },
    "prerequisite-targeting": {
      plan: "enterprise",
      displayName: "Prerequisite Targeting"
    },
    prerequisites: {
      plan: "pro",
      displayName: "Prerequisites"
    },
    "product-analytics-dashboards": {
      plan: "pro",
      displayName: "Product Analytics Dashboards"
    },
    "project-admin-role": {
      plan: "enterprise",
      displayName: "Project Admin Role"
    },
    "quantile-metrics": {
      plan: "pro",
      displayName: "Quantile Metrics"
    },
    "ramp-schedules": {
      plan: "pro",
      displayName: "Ramp Schedules"
    },
    redirects: {
      plan: "pro",
      displayName: "Redirects"
    },
    "regression-adjustment": {
      plan: "pro",
      displayName: "CUPED"
    },
    releases: {
      plan: "enterprise",
      displayName: "Releases"
    },
    "remote-evaluation": {
      plan: "pro",
      displayName: "Remote Evaluation"
    },
    "require-approvals": {
      plan: "enterprise",
      displayName: "Require Approvals"
    },
    "require-project-for-features-setting": {
      plan: "enterprise",
      displayName: "Require Project For Features Setting"
    },
    "require-project-for-sdk-connections-setting": {
      plan: "enterprise",
      displayName: "Require Project For Sdk Connections Setting"
    },
    "retention-metrics": {
      plan: "pro",
      displayName: "Retention Metrics"
    },
    "safe-rollout": {
      plan: "pro",
      displayName: "Safe Rollout"
    },
    saveSqlExplorerQueries: {
      plan: "pro",
      displayName: "Save SQL Explorer Queries"
    },
    "schedule-feature-flag": {
      plan: "pro",
      displayName: "Schedule Feature Flag"
    },
    "scheduled-revisions": {
      plan: "enterprise",
      displayName: "Scheduled Revisions"
    },
    scim: {
      plan: "enterprise",
      displayName: "SCIM"
    },
    "sequential-testing": {
      plan: "pro",
      displayName: "Sequential Testing"
    },
    "share-product-analytics-dashboards": {
      plan: "enterprise",
      displayName: "Share Product Analytics Dashboards"
    },
    simulate: {
      plan: "pro",
      displayName: "Simulate"
    },
    sso: {
      plan: "enterprise",
      displayName: "SSO"
    },
    "sticky-bucketing": {
      plan: "pro",
      displayName: "Sticky Bucketing"
    },
    teams: {
      plan: "enterprise",
      displayName: "Teams"
    },
    templates: {
      plan: "enterprise",
      displayName: "Templates"
    },
    "unlimited-managed-warehouse-usage": {
      plan: "pro",
      displayName: "Unlimited Managed Warehouse Usage"
    },
    "visual-editor": {
      plan: "pro",
      displayName: "Visual Editor"
    }
  };
  const {plan, displayName} = commercialFeatures[feature];
  const isEnterprise = plan === "enterprise";
  const defaultDescription = isEnterprise ? "is available on Enterprise plans." : "is available on Pro and Enterprise plans.";
  const planLabel = isEnterprise ? "Enterprise" : "Pro";
  const containerStyle = isEnterprise ? {
    backgroundColor: "color-mix(in srgb, var(--indigo-a3) 60%, transparent)"
  } : {
    backgroundColor: "color-mix(in srgb, var(--amber-a3) 60%, transparent)"
  };
  const badgeStyle = isEnterprise ? {
    boxShadow: "inset 0 0 0 1px var(--indigo-a8)",
    color: "var(--indigo-a11)"
  } : {
    boxShadow: "inset 0 0 0 1px var(--amber-a8)",
    color: "var(--amber-a11)"
  };
  return <div className="flex items-start gap-2 mb-4 p-3 text-sm leading-[1.4] rounded-lg" style={containerStyle} role="note">
      <span className="inline-flex items-center justify-center px-1.5 h-5 text-xs font-medium rounded-full shrink-0 leading-none" style={badgeStyle}>
        {planLabel}
      </span>
      <div className="flex-1 leading-[1.3]">
        <strong className="font-semibold">{displayName}</strong>{" "}
        {defaultDescription} {description}
      </div>
    </div>;
};

This page covers the core concepts you'll need to create and configure feature flags in GrowthBook.

## Feature Keys

Every feature is defined by a unique **key**. This is what your engineering team references in code when checking the value of a feature. Feature keys **cannot** be changed after creation, so take care when choosing one. If you make a mistake, delete the feature and create a new one.

<Frame>
  <img src="https://mintcdn.com/growthbook-ea15456d/giSZyh24PfnTkKz4/static/images/features/feature-create-feature-2.png?fit=max&auto=format&n=giSZyh24PfnTkKz4&q=85&s=3e076cb2b4c5a2f656ec5a4ca5be39ca" alt="Create Feature modal in GrowthBook" width="3502" height="1524" data-path="static/images/features/feature-create-feature-2.png" />
</Frame>

<Warning>
  **Naming Conventions**

  Feature keys must only include letters, numbers, hyphens (-), and underscores (\_).
</Warning>

## Feature State

Feature flags can be enabled or disabled. When a flag is disabled, GrowthBook excludes the feature from the API response. The feature evaluates to `null` and ignores all targeting and rules. In your app, the SDK will render the feature with the fallback value.

Here's an example from the JavaScript SDK:

```js theme={null}
const showNewCheckout = gb.isOn('new-checkout')
// Renders false if the feature is disabled

const buttonColor = gb.getFeatureValue('button-color', 'red')
// Renders 'red' if the feature is disabled
```

## Feature Types

Features can be a simple ON/OFF flag or a more complex data type (string, number, or JSON).

| Type        | Values               | Best for                                               | Example                                       |
| ----------- | -------------------- | ------------------------------------------------------ | --------------------------------------------- |
| **Boolean** | `true` / `false`     | Simple on/off toggles, kill switches, gradual rollouts | `show-onboarding-checklist`                   |
| **String**  | Any string           | Remote config, multivariate A/B tests                  | `button-color` set to `"red"`, `"blue"`, etc. |
| **Number**  | Any integer or float | Numeric configuration values                           | `results-per-page` set to `10`, `25`, `50`    |
| **JSON**    | Any JSON object      | Complex configuration, multiple values in one flag     | `{"maxRetries": 3, "timeout": 5000}`          |

**Boolean** flags are the most common. They're limited to two variations in A/B tests (on/off), so if you need more variations, like testing three different button colors, use a string, number, or JSON flag instead.

**JSON** flags also support JSON Schema validation, which lets you enforce the structure of the value before it reaches your application.

<CommercialFeature feature="json-validation" />

## Default Values

Each feature has a default value that's used when there are no matching rules for the user. A feature that is enabled on an environment with no rules uses the default value. Default values match the feature type.

Default values can be overridden by [**Rules**](/features/rules), which let you target specific users, roll out to a percentage of traffic, or run A/B experiments.

## What's Next

Now that you understand keys, types, and default values, the next concepts to explore are:

* **[Environments](/features/environments)** — Control where a feature is active (e.g., enabled in dev but not production). Each environment has its own SDK connection and independent set of rules.
* **[Rules](/features/rules)** — Override default values by targeting specific users, rolling out to a percentage of traffic, or running A/B experiments. See [Choosing a Rule Type](/features/rules#choosing-a-rule-type) for help picking the right approach.
* **[Targeting Conditions](/features/targeting)** — Define *who* sees a rule using attributes like user ID, country, or plan type.