What program in Windows 10 uses port 80?
You're likely referring to Skype as it's notorious to using port 80 without consideration. Open the command prompt and type netstat -a -b to get your answer. This question has been answered already and explains how to use netstat.
How can you find out which process is listening on a port on Windows?
It's probably the W3SVC (World Wide Web Publishing Service) service. See the answer below:
https://stackoverflow.com/a/31229606/1532882
- Click the start menu
- Type in Services
- Sort by Name
- Scroll down to World Wide Web Publishing Service (W3SVC) and disable it
Per phpvillian's answer, you can also run the following to help determine the culprit (make sure you open the command line with elevated privileges, e.g. "Run as administrator"):
netstat -a -b