ELI5: Explain Like I'm 5

Photo-lab timer

A photo-lab timer is a special clock that helps people who develop photos know when to do different things during the process. The timer has buttons that you press to set how long you want to do certain steps, like how long you want the chemicals to sit on the paper and how long you want the paper to dry.

When you start the timer, it counts down the time and lets you know when you are done with each step. This way, you can make sure that your photos turn out the way they are supposed to, with the right colors and sharpness. It's like having a little helper to remind you what to do and when to do it during the photo developing process.