"Katana" is a kind of traditional Japanese sword, and "owin", is some languages, means an agricultural building, a specialized kind of a barn. Jokes aside, it's not very nice to throw in some not very widely known words, especially abbreviations, and let people do a guesswork or a search for you. Was that so hard to provide at least some link?
But if you tried to find what you are interested in, you would easily find the answers. Please see:
https://en.wikipedia.org/wiki/Open_Web_Interface_for_.NET[
^],
http://www.asp.net/aspnet/overview/owin-and-katana[
^],
http://www.asp.net/aspnet/overview/owin-and-katana/an-overview-of-project-katana[
^].
Is that what you meant? Well, no matter what you read, it's hard to imagine that one would fail to figure out that OWIN is a standard for an interface, and the project Katana provides the actual set of OWIN-based components. Further reading should enlighten on the purpose of all that. Before you ask another question, please answer yourself to the following one: which part of the introductory text referenced above is unclear to you?
—SA
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