Computer-mediated communication (CMC) was a new type of medium over a decade ago and has been emerging rapidly in recent years. This book covers an exploratory study which was conducted among university students. The study investigated the effects of duration and frequency of messaging on impression and relational development in CMC environments. Results indicated that duration and frequency had significant main effects on impression and relational development in CMC environments. That is, long duration and high frequency of messaging result in significant higher impression and relational scores, respectively, in CMC environments. Since then, numerous research studies by various investigators related to this exploratory study has recently accumulated in the literature. This book will have wide implications in a variety of CMC environments. This book should help shed some light on the currently emerging CMC environments, and should be especially helpful for CMC researchers, university faculty and graduate students, and practioners including those in the areas of e-learning,e-commerce, and e-government, or anyone else who are interested in learning more about CMC.