Introduction to ASP.NET Core
ASP.NET Core is a significant redesign of ASP.NET. This topic introduces the new concepts in ASP.NET Core and explains how they help you develop modern web apps.
What is ASP.NET Core?
ASP.NET Core is a new open-source and cross-platform framework for building modern cloud based internet connected applications, such as web apps, IoT apps and mobile backends. ASP.NET Core apps can run on .NET Core or on the full .NET Framework. It was architected to provide an optimized development framework for apps that are deployed to the cloud or run on-premises. It consists of modular components with minimal overhead, so you retain flexibility while constructing your solutions. You can develop and run your ASP.NET Core apps cross-platform on Windows, Mac and Linux. ASP.NET Core is open source at GitHub.
Why build ASP.NET Core?
The first preview release of ASP.NET came out almost 15 years ago as part of the .NET Framework. Since then millions of developers have used it to build and run great web apps, and over the years we have added and evolved many capabilities to it.
ASP.NET Core has a number of architectural changes that result in a much leaner and modular framework. ASP.NET Core is no longer based on System.Web.dll. It is based on a set of granular and well factored NuGet packages. This allows you to optimize your app to include just the NuGet packages you need. The benefits of a smaller app surface area include tighter security, reduced servicing, improved performance, and decreased costs in a pay-for-what-you-use model.
With ASP.NET Core you gain the following foundational improvements:
A unified story for building web UI and web APIs
Integration of modern client-side frameworks and development workflows
A cloud-ready environment-based configuration system
Built-in dependency injection
New light-weight and modular HTTP request pipeline
Ability to host on IIS or self-host in your own process
Built on .NET Core, which supports true side-by-side app versioning
Ships entirely as NuGet packages
New tooling that simplifies modern web development
Build and run cross-platform ASP.NET apps on Windows, Mac and Linux
Open source and community focused
Build web UI and web APIs using ASP.NET Core MVC
You can build HTTP services that support multiple formats and have full support for content negotiation. See Formatting Response Data
Tag Helpers enable server-side code to participate in creating and rendering HTML elements in Razor files
You can create HTTP services with full support for content negotiation using custom or built-in formatters (JSON, XML)
Model Binding automatically maps data from HTTP requests to action method parameters
Model Validation automatically performs client and server side validation
For getting-started tutorials, see ASP.NET Core Tutorials
For in-depth introduction to ASP.NET Core concepts and architecture, see ASP.NET Core Fundamentals.
An ASP.NET Core app can use the .NET Core or .NET Framework runtime. For more information, see Choosing between .NET Core and .NET Framework.