domain and then deploy it in another domain later and he would like it to perform well in the new domain even though the new domain is different from how it was trained so for example you might want to train on a really clean image data set like image net but then deploy on users phones where the user is taking you know pictures in the dark or pictures while moving quickly and just pictures that aren't really centered or composed all that well when you take a normal machine learning model it often degrades really badly