From Dar

Asynchronous groups include possibly the largest portion of internet discussion groups, COPs and interest groups, identified by the character of retaining persistent messages which can be read at any time, but usually within a few days of having been posted. This contrasts with online chat, realtime messaging, voice messaging, IRC and video conferencing.

History

Historically, asynchronous many-to-many communications came into existence as a result of limited and expensive connectivity, particularly across widely seperated timezones bringing the earliest users of interconnected computers together for example across the Atlantic.

It quickly became apparent that asynchronous many-to-many discussions have unique characteristics which can make them extremely valuable. Once there existed a sufficient diversity of subscribers to an asynchronous group, then requests for help with even the most obscure and sometimes off-topic issues frequently received useful responses. Conversations in the asynchronous mode were sometimes found to be more thoughtful, reflective and carefully worded than the synchronous. This appears to suit some people more than others.

- increased take up - ubiquitous unmetered access - proliferation of groups - 

The illusion of more activity than reality

One phenomenon which the online researcher should beware of when planning to work with asynchronous groups is the illusion of greater activity levels than reality. This happens as a direct result of the asynchronous nature of the groups, which can cause a significantly different impression to be given when one first joins a group and tries to get the measure of it by reading back through the recently posted messages, contrasted with the experience of being a longer term member and reading the new messages from time to time as they arrive. Reading a previous thread at a single stretch can give the illusion of a group with lively continuing conversations, while the subscriber may perceive it quite differently, with little more than occasional attempts to get things going which nearly always fizzle out without much response.

"On checking back to the board to see if there were any replies I was diappointed to suddenly realise that the board is no where near as busy as I had thought. Ding! I had fallen into the asynchronous multiple timeline trap. When reading up on the converations for the first time, as (history) they sound brisk and lively, but when experiencing them as they develop in realtime, it can feel like there's nobody around. very slow or dead, even. A ghost house, or a party after everyone has left."