Psychiatrist John Suler offers some valuable insights into the way people interact and behave differently in cyberspace, than they do in face-to-face interaction. These are very strategic in relation to online evangelism and discipleship. You can read online or download the book in zipped format using the link below. Note that the e-book may not be as up-to-date as the online articles. (There are also other books on this subject.)
Available free online: