On February 22 in 1857 Heinrich Rudolf Hertz was born in Hamburg, Germany. His work in electromagnetism was important in advancing the state of physics at the end of the 19th century. In particular his modifying of Maxwell’s equations was instrumental in advancing the study of radio waves. Hertz’s experiments proved predictions made by Faraday and Maxwell and showed that radio waves move at the speed of light.
In recognition of Hertz’s great contributions, the SI unit for frequency was named hertz in 1960. The hertz replaced cycles per second (cps) and is now so common that most people are familliar with it as a unit of measurement.
The Wikipedia biography I found to be exceptionally well done with good links to further reading. The one addition I have is a link to an English translation of his book Electric Waves: Being Researches on the Propagation of Electric Action with Finite Velocity. This translation contains a preface written by Lord Kelvin.