The amateur radio activity, started in the first years of the XX century, is a most ancient activity in telecommunications field.
The definition of the Amateur Radio Service in the International Telecommunications rule by   International Telecommunications Union (I.T.U.), tells:
the amateur radio transmission must be personal and treating technical matters; they must have scarce importance to don't justify the use of telephonic, telegraphic and postal services.
The Administrations of each country establish the technical qualifications to release the radio operator licenses and define the amateur radio operational conditions.
Purpose of the national rules:
a) recognize the value of the voluntary non commercial telecommunication service, particularly in  cases of emergency and calamity;
b) recognize the amateur radio ability contribute to the progress of the radio;
c) encourage the amateur radio with rules that provide to bettering the operational ability and technique;
d) increase the quality of the operators and technical experienced in the radio field;
e) give the possibility to better the friendship and the international collaboration.
The Amateur Radio Service is the only way that allows to the people, distant many kilometers, to meet and know.
This is the general formulation of the Amateur Radio Service activity of  I.T.U. and I.A.R.U. (International Amateur Radio Union), the corporate body constituted from the union of the Amateur Radio Associations of the world.
This is therefore the image that each Amateur Radio must furnish to maintain his representative qualification of an important telecommunications service.
The dawn of the amateur radio
The amateur radio begins with the physical phenomenons studied by Maxwell and Hertz. Subsequently Guglielmo Marconi puts all in practical application. With the own intuitions, in 1895, Marconi develops the first system of telecommunication, invent the antenna and transmitting and receiving messages by radio. In 1898 connects Dover (England) and Vimereux (France) through the British channel; in 1901, the S letter, three points of the Morse alphabet, through the Atlantic Ocean between Cornwall (Poldhu) and St. John's - Newfoundland (Canada).
The first amateurs experimenters, receive the news that 3400 km of ocean, contrary to the affirmations of the official science, was jumped by the radio waves.
Many rudimentary transmitters and receivers was built in Europe and in America; the amateur radio movement started in all countries, until to arrive at his official recognition.
Who are the Amateur Radio
The majority are people that don't work in the field of the radio; but there is also technical professional that work in the electronic radio industry. 
The Amateur Radio are prevalently masculine, but there are also feminine enthusiastic Amateur Radio.
The Amateur Radio in the world overcome 2 million today, three  quarters are in Japan and U.S.A.
In Italy, the number of licenses is about 36000.
A license authorizes the Amateur Radio to communicate with Morse code (telegraphy) or by means the language (telephone).
The Amateur Radio use also teleprinter, television and digital transmission, encoded according to the more common standards. The Amateur Radio transmissions are on the assigned frequency by the international conventions. The license is issued by the government (in Italy, Ministero delle Comunicazioni). The transmission license, establishes the frequencies and transmission power and assigns a personal call sign to any Amateur Radio.
The prefix (the first part of the call sign) was assigned by the I.T.U. rules.
The last part of the call sign is composed by three letters and are assigned by "Ministero delle Comunicazioni".
To obtain the transmission license need get first the radio operator licence; to obtain the radio operator licence need to pass an exam at  Ministero delle Comunicazioni.
The examination is theoretical and practical, need also transmit and receive with the Morse code.
National and international organizations
The I.T.U., International Telecommunications Union, founded in 1865, is a specialized sector of the United Nations and his activity is divided in three Regions of the world.
The region 1 with Europe, Africa, the ex U.R.S.S. and few parts of Asia (Italy belongs to this region); the Region 2 with America;  the region 3 with Asia and the rest of the world.
The Amateurs Radio of the world are organized in National Associations.
The National Associations are part of the I.A.R.U., International Amateur Radio Union, founded in 1925 to represent and coordinate the activity in the world, especially towards the Governments.
The A.R.I. Associazione Radioamatori Italiani (already Associazione Radiotecnica Italiana), founded in 1927 and erect in Moral corporate body in 1950 is the Association that represents around 20.000 Amateur Radio.