Transfer Learning in NLP

First what is Transfer Learning? In these recent times, we have become very good at predicting a very accurate outcome with very good training models. But considering most of the machine learning tasks are domain specific, the trained models usually fail to generalize the conditions that it has never seen before. The real world is not like the trained data set, it contains lot of messy data and the model will make a ill prediction in such condition. The ability to transfer the knowledge of a pre-trained model into a new condition is generally referred to as transfer learning.