I spent a long time trying to figure out how to fix my Apache server on MAMP local host. I kept getting an error message saying that 'Apache couldn't start, because port 80 was in use by httpd'. Everyone seemed to think that another program was blocking port 80 (e.g. IIS, Skype, etc.). I tried finding these programs and removing them, but every time I did, the only program that was using port 80 was called System and I didn't think I could safely turn that off. I tried changing my port for Apache. Nothing worked until I found a solution saying that you could just change your php version in MAMP. I did this, and instantly Apache started working again.

My question is why would this happen? Why did changing my version of php fix Apache, and is there a way that port 80 could be blocked without another program being the reason.