What does the process identifier with the number 1 inside a Docker container mean?

In a Docker container, the process with ID 1 is the main (init) process inside the container. It starts first and manages the lifecycle of all other processes within the container. Unlike a typical system where PID 1 is init or systemd, in a container, PID 1 is the process that was started when the container was launched, such as your application or script. This process is responsible for handling signals and terminating the container.