Mohammad Hajarian is a Marie Curie Postdoctoral Fellow and an Assistant professor at the University Carlos III of Madrid. His research fields are Online Social Networks, Gamification, Human-computer Interaction, Interaction design, Recommendation Systems, Personalization, User Engagement, Data Science, and Online Marketing. He has been the programmer, designer, founder, and director of the Gegli social network since 2003, and he uses his social network website to implement and investigate most of his algorithms and frameworks in a real environment. During his professional career, he participated in several software projects, conferences, and workshops and worked as a reviewer in several prestigious journals and conferences. Furthermore, he taught 35+ computer courses in several universities and supervised 10+ theses at the graduate and postgraduate levels. He published 50+ articles and books in computer science and software engineering. And his innovative contributions have been exploited in the social media industry.