To explain what exactly Nikola Tesla invented is not so easy unless you happen to be an electrical engineer. But his many inventions are vital for things that we now take for granted: electric power and radio. Tesla’s background is also sometimes difficult to explain: he was born in the village of Smiljan, near Gospić (today’s Croatia) and was of Serbian descent, so both Croatia and Serbia have a legitimate claim to him (as, indeed, do the Americans – he became a US citizen!) See more about Tesla at the Technical Museum.