Synchronous vs. Asynchronous
From Social Patterns
Thinking about time as part of designing conversation systems is a critical consideration when deciding what type of communication tool to add to your social framework.
Public conversations in forums and streams, like Twitter, are often asynchronous and take place over extended periods of time. Individuals can be online at different times, participating in the conversation when it is convenient. Comments on a blog post which all refer to a single starting object are generally very easy to follow and can drift in and out of activity over a long period of time.
These types of conversations might benefit from threading or other tools in order for users to be able to follow the conversation. This adds complexity for the system as well as for end users but can aid in following the conversation across multiple users. Many of these types of conversations are public.
The real-time converations in Instant Messaging tools are synchronous and rely on all participants being present and engaged at the same time. These types of conversations can easily be followed because the conversation is happening in real time and is usually between a small number of participants. These conversations are often private.
Synchronous Communications utilize a fixed transmission frequency on both the sending and receiving ends to enable the participants in the communications process to communicate in real-time. For instance, a real-time chat session where all parties are available on a common platform at the same time. Normal telephone interactions are an example of synchronous communications.
Asynchronous communications, in contrast, can be carried out without the sender and the receiver being online or available at the same time. For instance, a message posted on a Message Board can communicate a message between two parties regardless of whether they are online at the same time. Voice Mail is another example of Asynchronous communications.