## 9 Conclusions  
For the research questions, it was found for RQ1 that passkeys face challenges concerning users' perceptions of them, slowing the adoption rate. For RQ2, even though the technology improves the security of user authentication, in doing so it provides a unique value proposition for users and corporations. For RQ3, determining the current level of adoption was not possible, as studies were found to be lacking in terms of the number of participants. We conclude by coming back to our initial defined research questions and answering them explicitly as follows:  
* RQ1: What are the main challenges that hinder passkey adoption for end users? The main challenges we see from the current academic research are, firstly, the user perception of passkeys. The passkey technology itself cannot directly address this; instead, it must be improved by improving user awareness and knowledge of the passkey technology. Secondly, despite significant improvements, current academia suggests there are key technical challenges regarding the account recovery, sharing, delegation, and transferability of passkeys. These challenges are especially relevant to the business adoption of passkeys and also negatively impact usability. Lastly, another aspect that can contribute to hindering passkey adoption is the lack of standardization, which can make it more troubling to implement passkeys from a technical perspective, and for users whose cognitive load associated with learning different user interface paradigms from multiple providers is further overwhelmed. * RQ2: What are the main potential improvements to enhance passkey adoption among end users? Despite the challenges, we see clear improvements in passkeys that can enhance adoption. Passkeys offer superior technical security over existing authentication methods, like passwords, while achieving high usability. Furthermore, through numerous research studies in the usability domain, passkeys have already made significant progress and improved their setup and usability during authentication processes. These aspects are critical for the user-centric considerations of the adoption of passkeys. RQ3: Is it possible to derive a relative number regarding the adoption of passkeys among end users for online authentication, and if so, what is the adoption rate? The first part of this research question can be answered with a tendency towards no. While some academic research tries to estimate the adoption rate among end users, we conclude that they do not provide enough evidence of being statistically significant. Other community-driven resources give at least an idea of the possibility of adopting passkeys from a user perspective, highlighting that more and more companies are offering support for this form of authentication. Overall, we note that passkeys do indeed have the potential to revolutionize the authentication processes in today's digital world. However, there is still a long way to go before the mass adoption of this new technology. While the current literature already focuses on solving the mentioned technical challenges, we see a clear need for more academic research focusing on effective strategies for enhancing the user perception of passkeys. In combination with the further expansion of passkey support among online services and companies, we believe that this will help increase the adoption rate of passkeys, ultimately leading to a more secure digital world that benefits both end users and companies. Conceptualization, A.M., A.R., M.B., O.H., M.P., G.C. and N.D.; methodology, A.M., A.R., M.B., O.H., M.P., G.C. and N.D.; validation, A.M., A.R., M.B., O.H., M.P., G.C. and N.D.; investigation, A.M., A.R., M.B. and O.H. ; resources, A.M., A.R., M.B. and O.H. ; data curation, A.M., A.R., M.B. and O.H. ; writing--original draft preparation, A.M., A.R., M.B., O.H., M.P., G.C. and N.D.; writing--review and editing, M.P., G.C. and N.D.; visualization, A.M., A.R., M.B., O.H., M.P., G.C. and N.D.; supervision, M.P., G.C. and N.D.; project administration, M.P., G.C.