I am new to Ubuntu 14.04. I installed lamp-server^
and after that Apache 2 auto-starts at the time of boot.
In Windows, I used WAMP server. It didn't auto start at the time of boot.
If it's idling it's probably irrelevant, even tough as any process Apache will consume some resources in order to keep running; an idling Apache should never be a big deal, however you can check this for yourself by running top -p $(pgrep -o apache)
.
Here's the output of the command on a Debian Jessie machine running Apache (it showcases the average load of the last 30 seconds):
Tasks: 1 total, 0 running, 1 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.2 us, 0.2 sy, 0.0 ni, 99.5 id, 0.1 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem: 3942096 total, 3515488 used, 426608 free, 271400 buffers
KiB Swap: 0 total, 0 used, 0 free. 2018532 cached Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3228 root 20 0 73488 4416 3216 S 0.0 0.1 0:00.01 apache2
In this case the CPU usage is almost null, and the memory usage is about the 0.1% of the total memory, hence ~4MB.
However as pointed out by prakharsingh95, leaving a server running with no purpose, aside from the intrinsic unusefulness, is a potential security flaw and (if that's a concern) also owns the port on which the server is listening.