We have to use port 80 for our server. But when I was trying to use it in Mac, it always said that the 80 is used, but I don't know which program uses it.

I searched it in Google, and someone said it's about apache, but I tried, which is not working. I found this: https://gist.github.com/kujohn/7209628 , but seems it's not working visiting our server by IP address.

I really don't know what's going on and how can I find out which program using port 80 and stop it.

Many thanks if anyone can help, I'm new using Mac. Thanks.