.NET Core is a modern, open-source, cross-platform framework developed by Microsoft for building a variety of applications, including web, cloud, microservices, IoT, and more. It is designed to run on Windows, Linux, and macOS, providing high performance and flexibility for developers.

1. Cross-Platform: Runs on Windows, Linux, and macOS.
2. Open Source: The source code is available on GitHub and contributions are welcome.
3. High Performance: Optimized for speed and scalability, suitable for cloud and microservices architectures.
4. Modular and Lightweight: Allows developers to include only the necessary libraries for their application.
5. Unified Development Model: Supports building web apps, APIs, desktop apps, and more with a consistent set of tools and libraries.
6. Built-in Dependency Injection: Enhances testability and maintainability of code.
7. Flexible Configuration: Supports configuration from multiple sources (JSON, environment variables, etc.).
8. Integrated Middleware Pipeline: Developers can compose request processing with middleware components.

1. Platform: .NET Core is cross-platform, while .NET Framework is Windows-only.
2. Architecture: .NET Core is modular and lightweight; .NET Framework is larger and more monolithic.
3. Performance: .NET Core is generally faster and more efficient.
4. Open Source: .NET Core is fully open source; .NET Framework is mostly closed-source.

.NET Core has built-in dependency injection. You register services in the Startup class and inject them into constructors where needed, promoting loose coupling and testability.