Book excerpt: This book presents the proceedings of the International Conference on Applied Cyber Security 2023 (ACS23), held in Dubai on the April 29, containing seven original contributions. Cybersecurity is continuously attracting the world’s attention and has gained in awareness and media coverage in the last decade. Not a single week passes without a major security incident that affects a company, sector, or governmental agencies. Most of the contributions are about applications of machine learning to accomplish several cybersecurity tasks, such as malware, network intrusion, and spam email detection. Similar trends of increasing AI applications are consistent with the current research and market trends in cybersecurity and other fields. We divided this book into two parts; the first is focused on malicious activity detection using AI, whereas the second groups AI applications to tackle a selection of cybersecurity problems. This book is suitable for cybersecurity researchers, practitioners, enthusiasts, as well as fresh graduates. It is also suitable for artificial intelligence researchers interested in exploring applications in cybersecurity. Prior exposure to basic machine learning concepts is preferable, but not necessary.