Azure Repos is a version control system offered as part of Microsoft’s Azure DevOps suite. It provides tools and features to manage source code repositories and collaborate on software development projects. Azure Repos supports two types of version control systems:

1. Git Repositories: Azure Repos offers Git-based version control, which is a distributed version control system. Git repositories are ideal for managing source code, tracking changes, and collaborating on projects. Git allows for branching and merging, which aids in parallel development and feature isolation.

2. Team Foundation Version Control (TFVC): TFVC is a centralized version control system provided by Azure Repos. It’s built on a client-server architecture and is more suitable for scenarios where centralized control is preferred over distributed development.

Key features of Azure Repos:

1. Branching and Merging: Git repositories in Azure Repos allow developers to create and manage branches for isolated feature development. This enables parallel work without affecting the main codebase. Merging tools are provided to bring changes from one branch to another.

2. Pull Requests: Git repositories support pull requests, which facilitate code review and collaboration. Developers can propose changes in one branch and request that they be merged into another. This process enables thorough review before code is merged.

3. Code Review: Azure Repos provides built-in code review features that allow team members to comment on code changes, suggest improvements, and discuss the changes before merging.

4. Build Integration: Azure Repos can be integrated with Azure Pipelines to automate the build and release process. Continuous integration (CI) and continuous deployment (CD) workflows can be defined to ensure code changes are automatically built, tested, and deployed.

5. Work Item Integration: Azure Repos can be linked with work items, such as user stories, tasks, and bugs, in Azure Boards. This helps in tracking code changes against specific work items and provides better visibility into project progress.

6. Security: Azure Repos provides security features such as branch policies, which enforce code review and certain criteria before merging. It also supports authentication and authorization mechanisms to control access to repositories.

7. Web-based Interface: Azure Repos offers a web-based interface that allows developers to view code, history, and branches, as well as perform various version control tasks without needing to use a command-line interface.

8. Integration: Azure Repos can be integrated with various development tools and IDEs, such as Visual Studio, Visual Studio Code, and Eclipse, to provide a seamless development experience.

Overall, Azure Repos in Azure DevOps is a versatile and feature-rich platform for managing source code repositories and supporting collaborative software development projects using both Git and TFVC version control systems.