Large web applications are usually developed by using a conceptual modeling language, where a scheme representing the web application is stepwise extended and refined. Thereby, modelers repeatedly perform modeling tasks like 'after having defined an entity type, add a page class for displaying the entity type’s content'. Since such tasks are performed again and again in a similar manner, it would be convenient to have scheme transformers that perform such tasks. This book introduces TBE (Transformers-By-Example), which is a language for defining and applying scheme transformers. TBE follows a by-example approach, where a modeler defines a transformer by giving a generic example of a scheme before and after transformation instead of specifying operations that perform the transformation. These operations are derived by TBE based on the provided generic examples. Transformers are thereby defined graphically and in a notation that is similar to one with which modelers are familiar.