In the evolution of communication technology post card is the one of the major turning point. The post cards are used widely to convey message in most effective forms. There are other kinds of posts like telegraphs with short sentences like “Emergency start immediately” and many others. The messages are mostly in the form of abbreviations. Telegraph is the long distance transmission of textual or symbolic messages without the physical exchange of an object bearing the message. It requires both the sender and receiver should know how to encode the message.

 After the evolution of radio signals the next generation of communication has started, where the messages are send through various frequencies .The messages here are not alone personal, they also communicated mass messages to the public. It has taken many years for this technology and it is still in use in many sectors like defense services, entertainment and few other. These radio signals are just audible in olden days. With the help of other devices and technologies these signals are transmitted to many different ways. Using of radio signals and wave frequencies are stepping-stones for many technologies which are present today like mobile phones.

 

 

With the increased technology in radio frequencies and invention of transmitters there are very huge changes in the communication technology. Initially using transmitters the messages are transferred only in the form of text for example Pagers.These pagers are still used in medical field by doctors, in information technology by system support engineers and few others.