The Owin Framework is a set of NuGet packages that can be used to build powerful and extremely scalable applications and services that are delivered over Http.
To take advantage of this open source project you will need to understand the fundamentals of computer programming. These tools are not designed to allow end-users to create websites.
The Owin Framework builds on OWIN, an open technology created by Microsoft to isolate web applications from the hosting platform. This means that applications based on OWIN can run on Apache, IIS, self-host (ie run as a standalone application that listens for Http requests directly) or any other hosting platform. This technology depends on the Microsoft .Net framework, and hence you must be using .Net as your application framework to take advantage of OWIN and the Owin Framework.
The Owin Framework is an open architecture, its design goal from the outset was to create a framework that allows components from many different developers to work seamlessly together with very little effort.
At this point enough NuGet packages have been authored that it is possible to create rich and highly scaleable websites and web services easily. This framework has been sucesfully used to build websites that serve millions of users, and you can reasonably expect each web server to be able to serve 10's thousands of Http request per second using this technology.
We eat our own dogfood, so this website is built entirely using the Owin Framework. You can see the source code for it here.