Continuous Integration (CI) in Azure DevOps is the practice of automatically integrating code changes from multiple contributors into a shared repository and verifying those changes through automated build and test processes. Azure DevOps provides a comprehensive CI/CD platform that supports a wide range of development technologies and workflows. Here’s an overview of how CI works in Azure DevOps:

1. Version Control: Developers work on their code changes in isolated branches within a version control system, such as Git, hosted on Azure DevOps.

2. Triggering Builds: CI builds are automatically triggered whenever code changes are pushed to the repository. You can configure CI triggers based on branch policies, pull requests, or specific folders.

3. Build Pipeline: A build pipeline defines the build process, including compiling code, running tests, and packaging artifacts. Azure DevOps offers a visual editor for creating build pipelines or allows you to define them as code using YAML.

4. Agent Pool: Azure DevOps provides a pool of build agents (hosted or self-hosted) that execute the build tasks. You can choose from Microsoft-hosted agents or set up your own self-hosted agents.

5. Build Steps: In the build pipeline, you specify the build steps, which can include tasks like restoring dependencies, building the application, running unit tests, and producing build artifacts.

6. Artifacts: Build artifacts, such as compiled binaries, libraries, and deployment packages, are generated during the build process. These artifacts are stored in Azure DevOps artifact feeds or external artifact repositories.

7. Testing: Automated tests, including unit tests, integration tests, and UI tests, can be integrated into the build pipeline to ensure code quality and functionality.

8. Code Analysis: Code analysis tools, like SonarQube or static code analyzers, can be integrated to identify code quality issues and security vulnerabilities.

9. Publishing Artifacts: After a successful build, the generated artifacts are published to Azure DevOps artifact feeds, making them available for subsequent stages in the release pipeline.

10. Notifications: Azure DevOps can send notifications and status updates to team members and stakeholders when builds succeed or fail.

11. Integration with Pull Requests: CI is often integrated with pull requests, allowing code changes to be automatically built and tested before merging into the main branch, ensuring that new code doesn’t introduce regressions.

12. Parallel Builds: Azure DevOps allows parallel execution of builds, enabling faster feedback and reducing build times, especially for large codebases.

13. Customization: Build pipelines are highly customizable, and you can add custom scripts, tasks, and extensions to tailor the build process to your project’s specific needs.

14. Continuous Deployment: CI is closely linked with Continuous Deployment (CD). Successful CI builds can trigger CD pipelines to automatically deploy the code changes to various environments, such as staging and production.

Azure DevOps provides a seamless CI/CD experience, allowing teams to automate the build and testing of their applications, leading to improved code quality, faster development cycles, and more reliable software releases. Whether you’re working on a small project or a large enterprise application, Azure DevOps CI can be adapted to meet your development and deployment requirements.