In his father's library, Marconi's imagination was nourished by Greek myths and by the works of great scientists such as Benjamin Franklin and Michael Faraday. In Leghorn, he learned the theoretical discipline needed for further study. The practical methods enabled him to build his first Morse telegraph transmitter at the age of 16.

In 1894, Marconi learned of Hertz’s experiments with electromagnetic waves. This led the young man to think as to how far waves could travel, by the account given by Hertz and became confident that Hertzian waves might be used in communication. Marconi began to experiment with the assistance of Professor Righi (a family friend and a physicist who taught at Bologna and Palermo Universities). He worked on his apparatus for sending and receiving telegraph messages through the air and soon was able to transmit coded signals across a distance of more than a mile. When the Italian government refused to acknowledge Marconi’s work, he went to England in 1896 and successfully, demonstrated his apparatus. In 1897, a message was sent from Queen Victoria to the Prince of Wales on the royal yacht. Marconi took a patent, which was the first ever granted for a practical system of wireless telegraphy. The same year, a company, later known as Marconi’s Wireless Telegraph Company Ltd. was formed for the commercial use of wireless. Marconi earned money through this company.

The first practical application of wireless was done in 1898, when Marconi followed the Kingstown Regetta in a tugboat and flashed the results in code to the offices of Dublin newspapers. The importance of wireless telegraphy in saving lives at sea was first demonstrated in 1899. The East Goodwin Sands lightship was stuck in a fog, and aid was summoned by wireless.

The year 1901 saw the greatest moment of Marconi’s life, when he transmitted signals across the Atlantic Ocean by wireless. This facilitated the daily news service for Trans Atlantic liners in 1904. The transmission of signal was made possible by the refraction and reflection of the signal in a conduction layer in the upper atmosphere, called the Ionosphere. Everybody thought that this was impossible. Believing that the radio waves traveled only in a straight line and followed the curvature of earth would not allow this. Marconi on December 12, 1901 proved that signals would follow the curvature of earth, by receiving the signals in St John, Newfoundland sent from a transmitter in Poldhu, at the southwestern tip of England.

Marconi increased the range of the spark coil transmitter by earthing one terminal and connecting the other to a tall antenna. He gave a tunable, systonic system by inserting capacitance and variable inductance between earth and the antenna. He shaped his antenna to beam the signals. This helped sending messages farther to larger distances. With this, Marconi was able to receive signals at Buenos Aires, Argentina, from Clifden, Ireland, and in 1918, he sent a message from England to Australia.

Stemming from his earlier observations, his speech heralded the technology of what later came to be called 'radio detection and ranging' or RADAR for short. Advances made by the Marconi company in marine direction-finding helped the development of these techniques.

The plan to link the British Empire by a network of wireless communication stations was first thought of in 1906. The project had been delayed by war and political conflict until 1924, but by this time, on board Elettra, his floating laboratory, Marconi had developed short-wave directional transmission. This new development, far superior to the long-wave high power system he had originally specified, was known as the Beam System. It was adopted by Canada, Australia, South Africa and India and the foundations were laid for the Imperial Wireless Chain - a revolution in world-wide communication.

Marconi returned to the study of very short wavelengths and in 1932, Marconi personally supervised the installation of the first microwave telephone link which connected the Vatican City with the Pope's summer residence, Castle Gandolfo.

In 1934, Marconi demonstrated equipment that helped navigation of ships possible. Marconi’s auto-alarm picked up distress signals when radio operators were off duty with sounds of a loud alarm. He was also first to use the ultra high frequency (UHF) waves for voice radio communication over short distances.