Phased rollouts, also known as incremental rollouts or staged deployments, refer to a software release strategy in which a new version of a product or feature is gradually introduced to a subset of users or customers, rather than being released to everyone all at once. This approach is often employed to mitigate risks, gather feedback, and ensure a smoother transition to new software versions. Here's how phased rollouts work:

1. Initial Release to a Subset: Instead of releasing a new software version to all users simultaneously, it is first deployed to a limited group of users. This initial subset could be a small percentage of the user base or a specific demographic.

2. Monitoring and Feedback Collection: During this phase, developers closely monitor the behavior of the users who received the update. They collect feedback, track performance metrics, and identify any issues that may arise.

3. Gradual Expansion: Based on the feedback and performance data, developers can make necessary adjustments or fixes before expanding the rollout. The rollout might be expanded to a larger group of users, ensuring that any critical issues are addressed before reaching a broader audience.

4. Iterative Process: The process continues iteratively, with the rollout gradually expanding to more users, monitoring and adjustments being made along the way. This approach allows developers to catch and fix issues early, reducing the impact of potential problems on the entire user base.

5. Full Release: After a series of successful phased rollouts, the new version is eventually released to the entire user base. By this point, most of the potential issues have been identified and resolved.

Benefits of phased rollouts include:

• Risk Mitigation: If there are any unexpected bugs or issues, they are contained to a smaller group of users initially, minimizing the overall impact.

• Feedback Gathering: Developers can gather real-world feedback from actual users, allowing them to make improvements and optimizations before a full release.

• Stable Deployment: Gradually expanding the rollout ensures that servers and infrastructure can handle the increased load as more users access the new version.

• Continuous Improvement: The iterative approach allows for continuous improvement based on user feedback and data.

• Enhanced User Experience: A smooth transition to new versions can lead to a better user experience and higher user satisfaction.

Phased rollouts are commonly used in software development, mobile app releases, and web services to ensure a successful and controlled introduction of new features or updates.