Why do we need to install nginx with thin on production setup, As thin is itself a web server. Every blog post people are using ruby+rails+nginx+thin?
As stated by Michael nginx balances thin (whatever that means). But another reason to use nginx in front of any ruby server is to serve static files (if you use page caching, they also can be served by nginx), which means requests wont even touch your ruby app, and increase a lot your performance. Also nginx although it seems to be the popular choice on the ruby/rails community, there are other alternatives like apache.