Online Discussion Groups
Online groups are a way to connect with people. It is like group meetings except that you can attend them at your leisure - online. Groups can be set up with friends, colleagues or with relatively unknown people who share similar passions.
It is similar to social networking sites except that online groups tend to be more specialized i.e. they tend to focus either on a particular topic or belong to a group of people (e.g. friends). Online groups are used most often to share information among members. This important aspect of groups makes them invaluable. Since groups tend to be specialized, most members in that particular group may be either professionals or hobbyists in that field of interest.
Groups require unity, networks require diversity. Groups require coherence, networks require autonomy. Groups require privacy or segregation, networks require openness. Groups require focus of voice, networks require interaction. - Stephen's Web
Groups can be effectively used in medicine to connect to other professionals for clinical case discussions, opine on recent journal articles, teaching or other similar uses.
Each group generally has a group leader or moderator. The moderator basically decides on who can become a member and what are their privileges. For example some members may only be able to view group discussions while others may be able to participate. Groups can communicate either my group emails or by posting online. Online posts can be commented on by other members.
There are a number of online services which allow to create groups but the most popular are Yahoo and Google Groups.
Google Groups

Besides the basic functions of a
group discussed above, Google groups provide a number
of features such as creating personalized web pages,
file sharing and member profiles.
