Most people use the kill command in its simplest form:

kill <PID>

and assume that this is all the command can do. Many users are unaware that kill supports numerous additional options and signal types.

In fact, kill does not simply “kill” a process — it sends a signal. By default, it sends SIGTERM (15), but it can send many other signals for different purposes, such as reloading a configuration (SIGHUP), pausing a process (SIGSTOP), resuming it (SIGCONT), or forcefully terminating it (SIGKILL).

for example:

kill -STOP <PID>

The kill command is therefore much more flexible than most people realize. It is a general-purpose signal-sending utility, not just a basic process termination tool.

For the curious, a complete list of signals:

kill -l