ASP.NET Core is a high-performance, cross-platform, and open-source framework. It allows you to build modern, cloud-enabled, and Internet-connected apps.
With ASP.NET Core, you can:
Some of the significant benefits of the ASP.NET Core framework over the ASP.NET framework are:
High Performance: ASP.NET Core framework is designed from scratch, keeping performance in mind. The ASP.NET team has focused on making the default web server, Kestrel, as fast as possible. TechEmpower, which has been running benchmarks on various frameworks, lists the ASP.NET Core with Kestrel as the fastest over 400 frameworks.
Cross-Platform: ASP.NET Core runs on the cross-platform .NET 5.0 platform. It is not tied to a Windows operating system, like the legacy ASP.NET framework. You can develop and run production-ready ASP.NET Core apps on Linux or a Mac. If you decide to use Linux, you don't have to pay for Windows licenses, resulting in significant cost savings.
Open Source: ASP.NET Core is open-source and actively developed on GitHub by thousands of developers all over the world, along with Microsoft. All the source code is hosted on GitHub for anyone to see, change and contribute back.
Along with these significant benefits, Microsoft lists the following benefits on its documentation page.
ASP.NET Core provides the following benefits:
A unified story for building web UI and web APIs.
Designed for testability.
Razor Pages makes coding page-focused scenarios easier and more productive.
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:
Tooling that simplifies modern web development.
Choosing ASP.NET Core lets you develop applications using new technologies such as Razor Pages and Blazor, in addition to the traditional Model-View-Controller approach.
However, it doesn't mean you have to switch from the ASP.NET framework right away. Though it's a more desirable choice in many aspects, you don't have to switch if you are happy with your current setup and don't have any pain points. This is especially true if you are maintaining a legacy ASP.NET application that is no longer actively developed. ASP.NET 4.x is a mature framework that provides the services needed to build enterprise-grade, server-based web apps on Windows.
Here are some situations where the older ASP.NET framework is still a better choice.
You are running on Windows servers and don't need cross-platform support for your applications.
You want a stable environment to work in that doesn't change frequently.
Have tight deadlines and release schedules.
You are maintaining a legacy app that's not getting any new features.