Synchronous Communication : It is a Real Time Communication. It happens at real Time. It occurs Instant. It is Fast. It is Active.
Examples : Face to Face, Telephonic, Instant Messaging, Video Conferencing, Webcams, MUDs, Chat, etc.
Asynchronous Communication : It is not
real time Communication. It happens as per schedules permit. It occurs delayed. It is Slow. It is Passive.
Examples : e-mail, Text Messaging, Newsgroups, Blogs, Social Media, etc.
Instant or DelaySynchronous / Asynchronous Communication