In 1956, DC Comics successfully revived superheroes, ushering in what became known as the Silver Age of comic books. Rather than bringing back the same Golden Age heroes, DC rethought them as new characters for the modern age. The Flash was the first revival, in the aptly named tryout comic book Showcase #4 (Oct. 1956).
This new Flash was Barry Allen, a police scientist who gained super-speed when bathed by chemicals after a shelf of them was struck by lightning. He adopted the name The Flash after reading a comic book featuring the Golden Age Flash. After several more appearances in Showcase, Allen’s character was given his own title, The Flash, the first issue of which was #105 (resuming where Flash Comics had left off).