To create an effective IA (information architecture) you first and foremost need to understand your users. A card sorting session can help you generate an idea, of how your IA should look – you simply ask users, how they would sort the content. To validate your IA and make sure this is the correct one, perform tree testing. Tree testing involves asking users to complete the usual tasks within the information architecture. By the success scores and time taken, you can judge whether the IA is effective and to what degree.