Communication between two people consists of transmitting and receiving. If both parties are performing both tasks effectively, there is good communication. This sounds very simple and obvious. In reality, it is difficult for most people to achieve. Communication is even difficult when concerned only with intellectual or cognitive content ─ explaining an idea or a theory, giving directions or instructions, delivering a message. Problems of vocabulary, colloquial expressions, semantic difficulties complicate transmitting. This makes reception more difficult. Even assuming efficient transmission, many people do not listen carefully enough to be efficient receivers anyway.