This talk will walk through the details of implementation of interfaces in MLIR. The interfaces (OpInterfaces, DialectInterfaces, TypeInterfaces, and AttributeInterfaces) are key components of MLIR extensibility. They are composed of a convenient user API through ODS (TableGen) as well as C++ wrappers. However there are many layers of indirection underlying their implementation, which are quite difficult to grasp with. It is a common complaint that it is impossible to debug or trace the code and understand how everything is fitting together.