Besides the link provided by @ig0774, you can also inspect the Microsoft.Office.Interop.Excel library directly. Add a reference to it in a project, right-click it > View in Object Browser (or even better, using Reflector), this will list every class and interface, with the methods, properties, etc... This is a good complement to the link above; the documentation helps in understanding usage, but the object browser will show you what interfaces are implemented, which is extremely useful in some places, like if you try to understand how to work with some events on the Application object.