In the book I will discuss both the experimental and theoretical aspects of exciton-exciton interaction in double quantum well structures, with an emphasis on how quantum well excitons can be trapped and made to move at the experimenter's will. I will pose many questions, some of which are answered in the book, some of which are intentionally left open. These open questions are still unsettled in the exciton community, and will hopefully convince the reader that this subject is still exciting, both on the experimental, and the theoretical side.