XAMPP/Apache: `Port 80 & 443 in use by "unknown program"`

XAMPP/Apache: `Port 80 & 443 in use by "unknown program"`

''Error Message.``
XAMPP Control Panel tells me when trying to start Apache:
[Apache] Problem detected!
[Apache] Port 80 in use by "unknown program"!
[Apache] Apache WILL NOT start without the configured ports free!
[Apache] You need to uninstall/disable/reconfigure the blocking
application
[Apache] or reconfigure Apache to listen on a different port
[Apache] Problem detected!
[Apache] Port 443 in use by "unknown program"!
[Apache] Apache WILL NOT start without the configured ports free!
[Apache] You need to uninstall/disable/reconfigure the blocking
application
[Apache] or reconfigure Apache to listen on a different port
When trying to dig for the program's name by using netstat:
$$ netstat -ab | more
TCP 0.0.0.0:80 XXX:0 ABHÖREN
[System]
--* ... *--
TCP 0.0.0.0:443 XXX:0 ABHÖREN
[System]
''Goal.``
I want to start Apache on these ports (without killing my system).
''Question.``
Why does my system need these ports, when other people run Apache on
80/443 without problems? Is it maybe because an application using these
ports was closed unexpectedly.
How can I force my system to release/free these ports without hurting my
system or harming animals?
Thanks for your answers - you're awesome.
[When anything (or everything) is unclear, please leave a comment.]