Asynchronous vs. Synchronous
Asynchronous vs Synchronous Communication
There are two general strategies for communicating in a blended course: Asynchronous and Synchronous. Each has its advantages and disadvantages.
Asynchronous communication and activities take place outside of real time. For example, a learner sends you an e-mail message. You later read and respond to the message. There is a time lag between the time the learner sent the message and you replied, even if the lag time is short. Bulletin board messages can be added at any time and read at your and the learners’ leisure; you do not read someone else’s message as it is being created, and you can take as much time as you need to respond to the post. Asynchronous activities take place whenever learners have the time to complete them. For example, viewing videos linked to the course site, reading a textbook, and writing a paper are all asynchronous activities .
There are some key advantages to asynchronous collaboration tools. For one thing, they enable flexibility. Participants can receive the information when it's most convenient for them. There's less pressure to act on the information or immediately respond in some way. People have time to digest the information and put it in the proper context and perspective. Another advantage is that some forms of asynchronous collaboration, such as email, are ubiquitous. These days, it's hard to find a co-worker, customer, business partner, consultant, or other party who doesn't have an email account.
The drawbacks of asynchronous collaboration are that they can lack a sense of immediacy and drama. There's less immediate interaction. Sometimes people have to wait hours, days, and even weeks to get a response to a message or feedback on a shared document. The lack of immediacy means that information can be out of date by the time someone views it. This is especially true in light of the rapid pace of change in today's business environment .
In contrast, synchronous, or real-time, communication takes place like a conversation. If your class uses only writing-based tools to communicate, the only synchronous communication possible is a chat session. Everyone gets online in the same chat room and types questions, comments, and responses in real time. Synchronous activities may include chat sessions, whiteboard drawings, and other group interactive work. If your class involves multimedia tools, synchronous communication might involve audio or video feeds to the computer. Some “online” courses require learners and teachers to get together at least once (or sometimes several times) in person, by conference call, or through closed-circuit television links .
One of the advantages of synchronous collaboration is its immediacy. You can send and receive information right away. This more closely resembles a face-to-face or telephone conversation between two or more people, so can present a more natural way of communicating. The sense of immediacy is more like to solicit a timely response from people. Synchronous collaboration, in general, is more interactive than asynchronous. 
The downside of synchronous collaboration is that not everyone uses it. Although instant messaging, chat, and other such tools are becoming more common, they're still not as ubiquitous as technology such as email. Another drawback is that synchronous collaboration is not as flexible as asynchronous. All the parties involved must be ready and willing to collaborate at a given moment-or the session doesn't work as well. Also, not everyone does well with this kind of collaboration, particularly people who like to think over what they want to communicate .
When should you use asynchronous and synchronous collaboration? Much of the decision-making on this involves common sense. Asynchronous collaboration, such as email and document sharing, can certainly be used for day-to-day communications when an urgent response isn't needed. This sort of communication is suitable for sending out broadcast messages that don't necessarily need to be acted on right away, or for corresponding with clients, customers. and business partners without putting pressure on them to respond immediately.
On the other hand, you wouldn't want to use asynchronous collaboration if you need immediate interaction with people or if you seek to collaborate with a large group at the same time. Email wouldn't work, for example, as the sole means of conducting a staff meeting.
Synchronous collaboration is ideal when the collaboration needs to be immediate and spontaneous, like a conversation between two or more people. Using real-time chat, instant messaging, electronic whiteboarding, and other such tools is appropriate for virtual meetings, where parties in remote locations are expected to participate and ask questions. In many cases, these types of collaborations might serve as supplements to telephone conference calls.
Synchronous collaboration wouldn't be suitable for situations that call for less immediate response or where parties aren't able to respond right away. For example, it might not work as a way to collaborate with customers on new product design or development.
For many organizations, asynchronous and synchronous collaboration will each prove valuable in their own way .