How did Denny O'Neil and Neal Adams change Batman comics in the modern era?

In the late 1960s and early 1970s, writer Dennis (“Denny”) O’Neil and artist Neal Adams were instrumental in shifting Batman away from the "kinder, gentler" tone that had dominated the character during the 1950s and 1960s.12

Their collaboration on an influential run of Batman stories helped restore the character's darker, more serious roots. Neal Adams, in particular, is widely credited with drawing the definitive modern version of the character, providing a visual aesthetic that aligned with this more mature approach. By moving away from the campier elements introduced in previous decades, O'Neil and Adams helped usher in the Bronze Age of comics, setting the stage for the gritty, complex portrayals of Batman that would follow in the 1980s.2