In IIS you can have multiple websites hosted on different application pools.You might have situation where you want to see your changes reflected at website A. What is good way to see your reflected changes? Does it require to restart the entire IIS and bring all other hosted website down?

No. There is no need to restart the IIS. You can click on application pool which serves that particular website and recycle it. This way if any client request in process get served by old worker process and
new requests will get served by new worker process instance. Here you haven’t made any website offline.

This is very helpful even if you don’t have enough traffic. The website can be your test environment.
Your colleague might be testing simultaneously when you are making changes. Your colleague request
will get served by old worker process which you just recycled. He or she would not get 404 kind of error
or Service unavailable kind of error.