Introduction to ASP.NET Core

ASP.NET Core is a cross-platform, high-performance, open-source framework for building modern, cloud-based, Internet-connected applications. With ASP.NET Core, you can:

• Build web apps and services, IoT apps, and mobile backends.
• Use your favorite development tools on Windows, macOS, and Linux.
• Deploy to the cloud or on-premises.
• Run on .NET Core or .NET Framework.

Why choose ASP.NET Core?

Millions of developers have used (and continue to use) ASP.NET 4.x to create web apps. ASP.NET Core is a redesign of ASP.NET 4.x, with architectural changes that result in a leaner, more modular framework.

ASP.NET Core provides the following benefits:

• A unified story for building web UI and web APIs.
• Architected for testability.
• Razor Pages makes coding page-focused scenarios easier and more productive.
• Blazor lets you use C# in the browser alongside JavaScript. Share server-side and client-side app logic all written with .NET.
• Ability to develop and run on Windows, macOS, and Linux.
• Open-source and community-focused.
• Integration of modern, client-side frameworks and development workflows.
• Support for hosting Remote Procedure Call (RPC) services using gRPC.
• A cloud-ready, environment-based configuration system.
• Built-in dependency injection.
• A lightweight, high-performance, and modular HTTP request pipeline.
• Ability to host on the following:
  • Kestrel
  • IIS
  • HTTP.sys
  • Nginx
  • Apache
  • Docker
• Side-by-side versioning.
• Tooling that simplifies modern web development.

Build web APIs and web UI using ASP.NET Core MVC

ASP.NET Core MVC provides features to build web APIs and web apps:

• The Model-View-Controller (MVC) pattern helps make your web APIs and web apps testable.
• Razor Pages is a page-based programming model that makes building web UI easier and more productive.
• Razor markup provides a productive syntax for Razor Pages and MVC views.
• Tag Helpers enable server-side code to participate in creating and rendering HTML elements in Razor files.
• Built-in support for multiple data formats and content negotiation lets your web APIs reach a broad range of clients, including browsers and mobile devices.
• Model binding automatically maps data from HTTP requests to action method parameters.
• Model validation automatically performs client-side and server-side validation.

Client-side development

ASP.NET Core integrates seamlessly with popular client-side frameworks and libraries, including Blazor, Angular, React, and Bootstrap. For more information, see Introduction to ASP.NET Core Blazor and related topics under Client-side development.

ASP.NET Core targeting .NET Framework

ASP.NET Core 2.x can target .NET Core or .NET Framework. ASP.NET Core apps targeting .NET Framework aren’t cross-platform—they run on Windows only. Generally, ASP.NET Core 2.x is made up of .NET Standard libraries. Libraries written with .NET Standard 2.0 run on any .NET platform that implements .NET Standard 2.0.

ASP.NET Core 2.x is supported on .NET Framework versions that implement .NET Standard 2.0:

• .NET Framework latest version is strongly recommended.
• .NET Framework 4.6.1 and later.

ASP.NET Core 3.0 and later will only run on .NET Core. For more details regarding this change, see A first look at changes coming in ASP.NET Core 3.0.

There are several advantages to targeting .NET Core, and these advantages increase with each release. Some advantages of .NET Core over .NET Framework include:

• Cross-platform. Runs on macOS, Linux, and Windows.
• Improved performance
• Side-by-side versioning
• New APIs
• Open-source

We’re working hard to close the API gap from .NET Framework to .NET Core. The Windows Compatibility Pack made thousands of Windows-only APIs available in .NET Core. These APIs weren’t available in .NET Core 1.x.

NOTE :

1. THE ABOVE TEXT IS TAKEN AS-IS FROM MICROSOFT WEBSITE @ https://docs.microsoft.com/en-au/aspnet/core/?view=aspnetcore-3.0 
2. ORIGINAL AUTHOR: Daniel Roth, Rick Anderson, and Shaun Luttin