What is interpersonal communication?
The ability to convey thoughts and ideas in a way that other people can understand. In other words being able to talk to people (or write) so that they know what you are saying, thinking, and feeling.
it is the ability to convey your thoughts without beating around the bushes
Interpersonal communication refers to the exchange of information or feelings via non-verbal or verbal messages. This happens between two or more people. This is one of the skills in communication. Check out http://www.skillsyouneed.com/ips/interpersonal-communication.html to learn more.