Communication is a process of conveying information, opinions or thoughts by speech, writing or signs. In the ancient times, messages were sent with the help of birds, blowing trumpets or beating drums. The process of communicating with a large number of people is known as mass communication. Newspaper, television, radio and internet are some important means of mass communication.
Semaphore is a visual way of communication invented for making maritime trade easy, where information is conveyed with the help of hand-held flags. After this, the Morse Code and the telegraph were invented.
Later inventions like telephone invented by Alexander Graham Bell and electronic mail (e-mail), have brought about an information revolution. Satellites also have made communication easier by enabling audio and video transmission. Satellites have helped largely in survey of forests, locating underground water and minerals, and even for exploring oil.
Satellites also help in general weather forecast and in early disaster warning, like storms and tsunamis.