Long exposure. For a very long time, this was a realm I could never venture into. Film was what it was, and the skills required for successful shots would have taken way too much of it. Back in the day, I was happy to catch a passing firetruck with its lights blinking. That was my first shot with light trails. It was also the last shot for another 25 years of photography.
The long exposure bug came back when I got a digital camera. A small Point and Shoot from Nikon. The “night modes” mostly tried to cancel the light trails in order to get decent pictures, but I found a way around that.