Depending on who you ask, the answers may vary. Let's start with the most basic definition of communication. Straight from Wikipedia:
Communication is a process of transferring information from one entity to another.
Your next question may be: What is an entity? For now, let's call the entity that transfers information Sender and the entity that receives the information Receiver.
The sender and the receiver can be people, animals or devices. It can also include other beings, but since this website is about communication in the workplace, we'll leave animals, dead people and angels out of this conversation.
Information can be a lot of different things depending on the context. People sometimes view information and the medium to transfer it as one and the same. They aren't. Let's distinguish between the information being sent that the medium used to send it.
The information can be:Words, gestures, drawings, paintings, songs, music.
The means can be: speeches, emails, blogs, forums, text messages, voice messages, poems, essays, books, newspapers, ads, articles, and practically anything you can speak through, write on or draw on.
MORE INFORMATION HERE : http://www.people-communicating.com/what-is-communication.html