What is Revit API
The Revit .NET API is a powerful tool that enables programming with any .NET compliant language such as Visual Basic.NET, C#, and C++/CLI. This API is specifically designed by Autodesk for power users and external application developers to seamlessly integrate their applications with Autodesk Revit. Using Revit API developer can create such addins add-ins to automate workflows effectively.
By leveraging the Revit API, developers can enhance their productivity and extend the functionality of Autodesk Revit.
About the Revit product center http://www.autodesk.com/revit