Creating websites today is not easy as it seems, therefore it is important to know the essential principle when developing new product for users. Knowing the essential principles is not enough, you will also need to know about what users think and feel is important on a website such as Stack Overflow. It is a question-and-answer website where it offers users the ability to post questions and receive answers from other users that uses the same website. This study will identify what is important for young adult developers on the website Stack Overflow and what they think, and feel is required in terms of usability on the website. In this study there will be a theoretical framework and it includes different aspects of usability: learnability, comprehensibility, navigation, flexibility, and discoverability. This theoretical framework has been created to be able to identify what is important for young adult developers on the website Stack Overflow. By using this theoretical framework, we can setup the data collection method which is interview and think-aloud-test. As for analysis of the data, content analysis has been used to analyze the results and the study reached its conclusion. The conclusion is that on a website like Stack Overflow, navigation, flexibility, and comprehensibility are the important aspects for young adult developers.