The long-term goal of isogeometric analysis is to integrate design and analysis. Hence, it is worth to take a brief look at how information can be extracted from CAD systems. The following discussion is by no means complete, but we aim to highlight some aspects of this topic. The chapter starts with general considerations for exchanging data between different computer software systems. Next, we provide a brief introduction to the Standard for the Exchange of Product Model Data (STEP). Finally, the idea of Bézier extraction is presented.