Abstract Within the past decade, the proliferation of multimedia social network communities, such as Napster, and YouTube where millions of users form a dynamically changing infrastructure to share content, have introduced the new concept of social networking that creates a technological revolution as well as brings new experiences to users. The massive content production poses new challenges to the scalable and reliable sharing of multimedia content over large and heterogeneous networks. It also raises critical issues of intellectual property protection and privacy issues. In a multimedia social network, users actively interact with each other, and such user dynamics not only influence each individual user but also affect the system performance. To provide a predictable and satisfactory level of service, it is of ample importance to understand the impact of human factors on multimedia social networks. Such an understanding provides fundamental guidelines to the better design of multimedia systems and networking, and offers more secure and personalized services. For example, in a peer-to-peer file-sharing system, users pool together the resources and cooperate with each other to provide an inexpensive, highly scalable, and robust platform for distributed data sharing. However, since the nature of participation in many multimedia social networks is often voluntary and unregulated, there is a need to provide incentives and mechanism to stimulate cooperation among users to improve system performance. The influence of human behavior and factors has seldom been recognized in signal and image processing research. Therefore, first in this talk the goal is to illustrate why understanding of human factors and behavior plays an important role in designing and improving multimedia communications and security. Such a journey leads us to reconsider many classical signal and image processing problems from the concept/notion of social networking. The second goal of the talk is to demonstrate that the social networking approach can indeed offer a new and unified view to many classical problems and has the potential of becoming a new signal and image processing paradigm. Bio of Ray Liu Dr. Liu received the B.S. degree from the National Taiwan University in 1983, and the Ph.D. degree from UCLA in 1990, both in electrical engineering. He is Professor and Associate Chair of Graduate Studies and Research of Electrical and Computer Engineering Department, University of Maryland, College Park. Dr. Liu is Director of Communications and Signal Processing Laboratories and leads the Maryland Signals and Information Group (SIG) with research contributions that encompass broad aspects of wireless communications and networking; multimedia communications and signal processing; information forensics and security; biomedical imaging and bioinformatics; and signal processing algorithms and architectures, in which he has published over 10 books and 500 refereed papers. Dr. Liu is the recipient of numerous honors and awards including the 1994 National Science Foundation Young Investigator Award; best paper awards from IEEE Signal Processing Society, Vehicular Technology Society, and EURASIP; IEEE Signal Processing Society 2004 Distinguished Lecturer; and EURASIP 2004 Meritorious Service Award. Dr. Liu is the recipient of 2009 IEEE Signal Processing Society Technical Achievement Award. He is a Fellow of the IEEE and AAAS. His research was featured as one of seven technologies that IEEE believes will have the world changing implications on the way humans interact with machines, the world and each other, in honor of IEEE's 125th Anniversary. Dr. Liu is recognized by Thomson Reuters as a Highly Cited Researcher. Dr. Liu is President-Elect of IEEE Signal Processing Society. He was Vice President - Publications (2006-08) and has been a member-at-large (2004-05) on the Board of Governor of IEEE Signal Processing Society. He is a founder of Asia-Pacific Association of Signal and Information Processing (APSIPA). Dr. Liu was the Editor-in-Chief of IEEE Signal Processing Magazine, the founding Editor-in-Chief of EURASIP Journal on Applied Signal Processing (JASP, now called EURASIP Journal on Advances in Signal Processing), and the prime architect and proposer of IEEE Trans. on Information Forensics and Security and IEEE Journal on Selected Topics of Signal Processing.