What is wrong with my server?

Okay, so I have a Minecraft server and I went online to a port testing service ( I did forward port 25565)
and the service said my port was open and my server was fine, but when my friends try to get on their computer doesn't even recognize the IP. What is wrong?

Did you give them your external IP?

You can see yours here: http://www.whatismyip.com/

Check ip, connection

Check your Ip connection speed and connection details etc properly.