# Feature Experimentation & Rollout
Feature Experimentation & Rollout (FE\&R) is AB Tasty's server-side experimentation solution for managing feature deployments using feature **flags** and **context keys**. It enables secure, controlled backend experimentation with seamless server-side implementation.
### Features
* **A/B experiments**: Segment your audience to test multiple feature variations simultaneously.
* **Feature Flags**: Toggle new features on or off without code deployment for rapid iteration and agile development.
* **Custom Targeting**: Target specific user segments by location, device, behavior, or custom criteria.
* **Real-Time Analytics**: Access real-time data and insights for each feature variation.
* **Gradual Rollouts**: Deploy features to limited audience first to ensure stability before wider release.
### **Server-Side vs Client-Side experiments**
Server-side and client-side experiments differ in implementation and use cases:
#### **Server-Side experiments**:
* **Execution**: experiments are run on the server before content reaches the user's device.
* **Use Cases**: Backend logic, database interactions, or ensuring consistency across devices and sessions.
* **Advantages**: Greater control, secure handling of sensitive data, minimal client-side performance impact.
* **Implementation in AB Tasty**: Integrates with your backend systems through APIs and feature flags for precise experimentation and real-time updates.
#### **Client-Side experiments**:
* **Execution**: Runs in the user's browser or app after receiving content from the server.
* **Use Cases**: UI/UX changes, front-end design adjustments, or experiments without sensitive data requirements.
* **Advantages**: No backend changes required, quick setup, immediate visual feedback.
* **Implementation in AB Tasty**: Use the web editor for browser-based changes and JavaScript for advanced testing and targeting.
AB Tasty supports both server-side and client-side experimentation with integrated tools for management, tracking, and analysis.
### **Flags and Context keys**
Feature Experimentation and Rollout (FE\&R) allows you to manage feature deployments using flags and context keys. This approach helps control access to features and perform targeted testing.
#### **Feature Flags**
Feature flags toggle feature availability without code deployment. With flags, you can:
* Gradually release features to specific user segments.
* A/B test different feature versions across user groups.
* Disable features immediately if issues arise.
#### **Context Keys**
Context keys define conditions for feature access based on user attributes or behavior. Use context keys to:
* Personalize contents based on user preferences or location.
* Target rollouts using specific parameters like device type or user history.
### **Installing FE\&R SDK**
To use FE\&R, you need to install the [FE\&R SDK](https://docs.developers.flagship.io/docs/getting-started-with-flagship)
### Tutorials
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