The early history of radio is the history of technology that produced radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio. Radio development began as "wireless telegraphy". Later radio history increasingly involves matters of programming and content.
Various scientists proposed that electricity and magnetism, both capable of causing attraction and repulsion of objects, were linked. In 1802 Gian Domenico Romagnosi suggested the relationship between electric current and magnetism, but his reports went unnoticed. In 1820 Hans Christian Ørsted performed a widely known experiment on man-made electric current and magnetism. He demonstrated that a wire carrying a current could deflect a magnetized compass needle. Ørsted's experiments discovered the relationship between electricity and magnetism in a very simple experiment. Ørsted's work influenced André-Marie Ampère to produce a theory of electromagnetism. During its early development and long after wide use of the technology, disputes persisted as to who could claim sole credit for this obvious boon to mankind. Closely related, radio was developed along with two other key inventions, the telegraph and the telephone.
In the late 19th century it was clear to various scientists and experimenters that wireless communication was possible. Various theoretical and experimental innovations led to the development of radio and the communication system we know today. Some early work was done by local effects and experiments of electromagnetic induction. Many understood that there was nothing similar to the "ethereal telegraphy" and telegraphy by induction; the phenomena being wholly distinct. Wireless telegraphy was beginning to take hold and the practice of transmitting messages without wires was being developed. Many people worked on developing the devices and improvements.